postcss

Create a new Processor instance that will apply plugins as CSS processors.

let postcss = require('postcss')

postcss(plugins).process(css, { from, to }).then(result => {
  console.log(result.css)
})

Returns default. Processor to process multiple CSS.

postcss.AtRule

Type: typeof default.

postcss.Comment

Type: typeof default.

postcss.Container

Type: typeof default.

postcss.CssSyntaxError

Type: typeof default.

postcss.Declaration

Type: typeof default.

postcss.Input

Type: typeof default.

postcss.Node

Type: typeof default.

postcss.Result

Type: typeof default.

postcss.Root

Type: typeof default.

postcss.Rule

Type: typeof default.

postcss.Warning

Type: typeof default.

postcss.fromJSON

Rehydrate a JSON AST (from Node#toJSON) back into the AST classes.

const json = root.toJSON()
// save to file, send by network, etc
const root2  = postcss.fromJSON(json)

Type: JSONHydrator.

postcss.list

Contains the list module.

Type: List.

postcss.parse

Parses source css and returns a new Root or Document node, which contains the source CSS nodes.

// Simple CSS concatenation with source map support
const root1 = postcss.parse(css1, { from: file1 })
const root2 = postcss.parse(css2, { from: file2 })
root1.append(root2).toResult().css

Type: Parser<default>.

postcss.stringify

Default function to convert a node tree into a CSS string.

Type: Stringifier.

postcss.atRule()

Creates a new AtRule node.

Returns default. New at-rule node.

postcss.comment()

Creates a new Comment node.

Returns default. New comment node

postcss.decl()

Creates a new Declaration node.

Returns default. New declaration node.

postcss.document()

Creates a new Document node.

Returns default. New document node.

postcss.root()

Creates a new Root node.

Returns default. New root node.

postcss.rule()

Creates a new Rule node.

Returns default. New rule node.

AtRule

Represents an at-rule.

Once (root, { AtRule }) {
  let media = new AtRule({ name: 'media', params: 'print' })
  media.append(…)
  root.append(media)
}

If it’s followed in the CSS by a {} block, this node will have a nodes property representing its children.

const root = postcss.parse('@charset "UTF-8"; @media print {}')

const charset = root.first
charset.type  //=> 'atrule'
charset.nodes //=> undefined

const media = root.last
media.nodes   //=> []

AtRule#name

The at-rule’s name immediately follows the @.

const root  = postcss.parse('@media print {}')
media.name //=> 'media'
const media = root.first

Type: string.

AtRule#nodes

An array containing the container’s children.

const root = postcss.parse('a { color: black }')
root.nodes.length           //=> 1
root.nodes[0].selector      //=> 'a'
root.nodes[0].nodes[0].prop //=> 'color'

Type: ChildNode[].

AtRule#params

The at-rule’s parameters, the values that follow the at-rule’s name but precede any {} block.

const root  = postcss.parse('@media print, screen {}')
const media = root.first
media.params //=> 'print, screen'

Type: string.

AtRule#parent

The node’s parent node.

root.nodes[0].parent === root

Type: default<ChildNode>.

AtRule#raws

Information to generate byte-to-byte equal node string as it was in the origin input.

Every parser saves its own properties, but the default CSS parser uses:

• before: the space symbols before the node. It also stores * and _ symbols before the declaration (IE hack).
• after: the space symbols after the last child of the node to the end of the node.
• between: the symbols between the property and value for declarations, selector and { for rules, or last parameter and { for at-rules.
• semicolon: contains true if the last child has an (optional) semicolon.
• afterName: the space between the at-rule name and its parameters.
• left: the space symbols between /* and the comment’s text.
• right: the space symbols between the comment’s text and */.
• important: the content of the important statement, if it is not just !important.

PostCSS cleans selectors, declaration values and at-rule parameters from comments and extra spaces, but it stores origin content in raws properties. As such, if you don’t change a declaration’s value, PostCSS will use the raw value with comments.

const root = postcss.parse('a {\n  color:black\n}')
root.first.first.raws //=> { before: '\n  ', between: ':' }

Type: AtRuleRaws.

AtRule#source

The input source of the node.

The property is used in source map generation.

If you create a node manually (e.g., with postcss.decl()), that node will not have a source property and will be absent from the source map. For this reason, the plugin developer should consider cloning nodes to create new ones (in which case the new node’s source will reference the original, cloned node) or setting the source property manually.

decl.source.input.from //=> '/home/ai/a.sass'
decl.source.start      //=> { line: 10, column: 2 }
decl.source.end        //=> { line: 10, column: 12 }

// Bad
const prefixed = postcss.decl({
  prop: '-moz-' + decl.prop,
  value: decl.value
})

// Good
const prefixed = decl.clone({ prop: '-moz-' + decl.prop })

if (atrule.name === 'add-link') {
  const rule = postcss.rule({ selector: 'a', source: atrule.source })
  atrule.parent.insertBefore(atrule, rule)
}

Type: Source.

AtRule#type

tring representing the node’s type. Possible values are root, atrule, rule, decl, or comment.

new Declaration({ prop: 'color', value: 'black' }).type //=> 'decl'

Type: "atrule".

AtRule#first

The container’s first child.

rule.first === rules.nodes[0]

AtRule#last

The container’s last child.

rule.last === rule.nodes[rule.nodes.length - 1]

AtRule#after()

Insert new node after current node to current node’s parent.

Just alias for node.parent.insertAfter(node, add).

decl.after('color: black')

Returns default. This node for methods chain.

AtRule#append()

Inserts new nodes to the end of the container.

const decl1 = new Declaration({ prop: 'color', value: 'black' })
const decl2 = new Declaration({ prop: 'background-color', value: 'white' })
rule.append(decl1, decl2)

root.append({ name: 'charset', params: '"UTF-8"' })  // at-rule
root.append({ selector: 'a' })                       // rule
rule.append({ prop: 'color', value: 'black' })       // declaration
rule.append({ text: 'Comment' })                     // comment

root.append('a {}')
root.first.append('color: black; z-index: 1')

Returns default. This node for methods chain.

AtRule#assign()

Assigns properties to the current node.

decl.assign({ prop: 'word-wrap', value: 'break-word' })

Returns default. Current node to methods chain.

AtRule#before()

Insert new node before current node to current node’s parent.

Just alias for node.parent.insertBefore(node, add).

decl.before('content: ""')

Returns default. This node for methods chain.

AtRule#cleanRaws()

Clear the code style properties for the node and its children.

node.raws.before  //=> ' '
node.cleanRaws()
node.raws.before  //=> undefined

AtRule#clone()

Returns an exact clone of the node.

The resulting cloned node and its (cloned) children will retain code style properties.

decl.raws.before    //=> "\n  "
const cloned = decl.clone({ prop: '-moz-' + decl.prop })
cloned.raws.before  //=> "\n  "
cloned.toString()   //=> -moz-transform: scale(0)

Returns default. Clone of the node.

AtRule#cloneAfter()

Shortcut to clone the node and insert the resulting cloned node after the current node.

Returns default. New node.

AtRule#cloneBefore()

Shortcut to clone the node and insert the resulting cloned node before the current node.

decl.cloneBefore({ prop: '-moz-' + decl.prop })

Returns default. New node

AtRule#each()

Iterates through the container’s immediate children, calling callback for each child.

Returning false in the callback will break iteration.

This method only iterates through the container’s immediate children. If you need to recursively iterate through all the container’s descendant nodes, use Container#walk.

Unlike the for {}-cycle or Array#forEach this iterator is safe if you are mutating the array of child nodes during iteration. PostCSS will adjust the current index to match the mutations.

const root = postcss.parse('a { color: black; z-index: 1 }')
const rule = root.first

for (const decl of rule.nodes) {
  decl.cloneBefore({ prop: '-webkit-' + decl.prop })
  // Cycle will be infinite, because cloneBefore moves the current node
  // to the next index
}

rule.each(decl => {
  decl.cloneBefore({ prop: '-webkit-' + decl.prop })
  // Will be executed only for color and z-index
})

Returns void | false. Returns false if iteration was broke.

AtRule#error()

Returns a CssSyntaxError instance containing the original position of the node in the source, showing line and column numbers and also a small excerpt to facilitate debugging.

If present, an input source map will be used to get the original position of the source, even from a previous compilation step (e.g., from Sass compilation).

This method produces very useful error messages.

if (!variables[name]) {
  throw decl.error(`Unknown variable ${name}`, { word: name })
  // CssSyntaxError: postcss-vars:a.sass:4:3: Unknown variable $black
  //   color: $black
  // a
  //          ^
  //   background: white
}

Returns default. Error object to throw it.

AtRule#every()

Returns true if callback returns true for all of the container’s children.

const noPrefixes = rule.every(i => i.prop[0] !== '-')

Returns boolean. Is every child pass condition.

AtRule#index()

Returns a child’s index within the Container#nodes array.

rule.index( rule.nodes[2] ) //=> 2

Returns number. Child index.

AtRule#insertAfter()

Insert new node after old node within the container.

Returns default. This node for methods chain.

AtRule#insertBefore()

Insert new node before old node within the container.

rule.insertBefore(decl, decl.clone({ prop: '-webkit-' + decl.prop }))

Returns default. This node for methods chain.

AtRule#next()

Returns the next child of the node’s parent. Returns undefined if the current node is the last child.

if (comment.text === 'delete next') {
  const next = comment.next()
  if (next) {
    next.remove()
  }
}

Returns ChildNode. Next node.

AtRule#positionBy()

Get the position for a word or an index inside the node.

Returns Position. Position.

AtRule#positionInside()

Convert string index to line/column.

Returns Position. Symbol position in file.

AtRule#prepend()

Inserts new nodes to the start of the container.

const decl1 = new Declaration({ prop: 'color', value: 'black' })
const decl2 = new Declaration({ prop: 'background-color', value: 'white' })
rule.prepend(decl1, decl2)

root.append({ name: 'charset', params: '"UTF-8"' })  // at-rule
root.append({ selector: 'a' })                       // rule
rule.append({ prop: 'color', value: 'black' })       // declaration
rule.append({ text: 'Comment' })                     // comment

root.append('a {}')
root.first.append('color: black; z-index: 1')

Returns default. This node for methods chain.

AtRule#prev()

Returns the previous child of the node’s parent. Returns undefined if the current node is the first child.

const annotation = decl.prev()
if (annotation.type === 'comment') {
  readAnnotation(annotation.text)
}

Returns ChildNode. Previous node.

AtRule#push()

Add child to the end of the node.

rule.push(new Declaration({ prop: 'color', value: 'black' }))

Returns default. This node for methods chain.

AtRule#rangeBy()

Get the range for a word or start and end index inside the node. The start index is inclusive; the end index is exclusive.

Returns Range. Range.

AtRule#raw()

Returns a Node#raws value. If the node is missing the code style property (because the node was manually built or cloned), PostCSS will try to autodetect the code style property by looking at other nodes in the tree.

const root = postcss.parse('a { background: white }')
root.nodes[0].append({ prop: 'color', value: 'black' })
root.nodes[0].nodes[1].raws.before   //=> undefined
root.nodes[0].nodes[1].raw('before') //=> ' '

Returns string. Code style value.

AtRule#remove()

Removes the node from its parent and cleans the parent properties from the node and its children.

if (decl.prop.match(/^-webkit-/)) {
  decl.remove()
}

Returns default. Node to make calls chain.

AtRule#removeAll()

Removes all children from the container and cleans their parent properties.

rule.removeAll()
rule.nodes.length //=> 0

Returns default. This node for methods chain.

AtRule#removeChild()

Removes node from the container and cleans the parent properties from the node and its children.

rule.nodes.length  //=> 5
rule.removeChild(decl)
rule.nodes.length  //=> 4
decl.parent        //=> undefined

Returns default. This node for methods chain.

AtRule#replaceValues()

Passes all declaration values within the container that match pattern through callback, replacing those values with the returned result of callback.

This method is useful if you are using a custom unit or function and need to iterate through all values.

root.replaceValues(/\d+rem/, { fast: 'rem' }, string => {
  return 15 * parseInt(string) + 'px'
})

Returns default. This node for methods chain.

AtRule#replaceWith()

Inserts node(s) before the current node and removes the current node.

AtRule: {
  mixin: atrule => {
    atrule.replaceWith(mixinRules[atrule.params])
  }
}

Returns default. Current node to methods chain.

AtRule#root()

Finds the Root instance of the node’s tree.

root.nodes[0].nodes[0].root() === root

Returns default. Root parent.

AtRule#some()

Returns true if callback returns true for (at least) one of the container’s children.

const hasPrefix = rule.some(i => i.prop[0] === '-')

Returns boolean. Is some child pass condition.

AtRule#toJSON()

Fix circular links on JSON.stringify().

Returns object. Cleaned object.

AtRule#toString()

Returns a CSS string representing the node.

new Rule({ selector: 'a' }).toString() //=> "a {}"

Returns string. CSS string of this node.

AtRule#walk()

Traverses the container’s descendant nodes, calling callback for each node.

Like container.each(), this method is safe to use if you are mutating arrays during iteration.

If you only need to iterate through the container’s immediate children, use Container#each.

root.walk(node => {
  // Traverses all descendant nodes.
})

Returns void | false. Returns false if iteration was broke.

AtRule#walkAtRules()

Traverses the container’s descendant nodes, calling callback for each at-rule node.

If you pass a filter, iteration will only happen over at-rules that have matching names.

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

root.walkAtRules(rule => {
  if (isOld(rule.name)) rule.remove()
})

let first = false
root.walkAtRules('charset', rule => {
  if (!first) {
    first = true
  } else {
    rule.remove()
  }
})

Returns void | false. Returns false if iteration was broke.

AtRule#walkComments()

Traverses the container’s descendant nodes, calling callback for each comment node.

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

root.walkComments(comment => {
  comment.remove()
})

Returns void | false. Returns false if iteration was broke.

AtRule#walkDecls()

Traverses the container’s descendant nodes, calling callback for each declaration node.

If you pass a filter, iteration will only happen over declarations with matching properties.

root.walkDecls(decl => {
  checkPropertySupport(decl.prop)
})

root.walkDecls('border-radius', decl => {
  decl.remove()
})

root.walkDecls(/^background/, decl => {
  decl.value = takeFirstColorFromGradient(decl.value)
})

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

Returns void | false. Returns false if iteration was broke.

AtRule#walkRules()

Traverses the container’s descendant nodes, calling callback for each rule node.

If you pass a filter, iteration will only happen over rules with matching selectors.

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

const selectors = []
root.walkRules(rule => {
  selectors.push(rule.selector)
})
console.log(`Your CSS uses ${ selectors.length } selectors`)

Returns void | false. Returns false if iteration was broke.

AtRule#warn()

This method is provided as a convenience wrapper for Result#warn.

  Declaration: {
    bad: (decl, { result }) => {
      decl.warn(result, 'Deprecated property bad')
    }
  }

Returns default. Created warning object.

Comment

Represents a comment between declarations or statements (rule and at-rules).

Once (root, { Comment }) {
  let note = new Comment({ text: 'Note: …' })
  root.append(note)
}

Comments inside selectors, at-rule parameters, or declaration values will be stored in the raws properties explained above.

Comment#parent

The node’s parent node.

root.nodes[0].parent === root

Type: default<ChildNode>.

Comment#raws

Information to generate byte-to-byte equal node string as it was in the origin input.

Every parser saves its own properties, but the default CSS parser uses:

• before: the space symbols before the node. It also stores * and _ symbols before the declaration (IE hack).
• after: the space symbols after the last child of the node to the end of the node.
• between: the symbols between the property and value for declarations, selector and { for rules, or last parameter and { for at-rules.
• semicolon: contains true if the last child has an (optional) semicolon.
• afterName: the space between the at-rule name and its parameters.
• left: the space symbols between /* and the comment’s text.
• right: the space symbols between the comment’s text and */.
• important: the content of the important statement, if it is not just !important.

PostCSS cleans selectors, declaration values and at-rule parameters from comments and extra spaces, but it stores origin content in raws properties. As such, if you don’t change a declaration’s value, PostCSS will use the raw value with comments.

const root = postcss.parse('a {\n  color:black\n}')
root.first.first.raws //=> { before: '\n  ', between: ':' }

Type: CommentRaws.

Comment#source

The input source of the node.

The property is used in source map generation.

If you create a node manually (e.g., with postcss.decl()), that node will not have a source property and will be absent from the source map. For this reason, the plugin developer should consider cloning nodes to create new ones (in which case the new node’s source will reference the original, cloned node) or setting the source property manually.

decl.source.input.from //=> '/home/ai/a.sass'
decl.source.start      //=> { line: 10, column: 2 }
decl.source.end        //=> { line: 10, column: 12 }

// Bad
const prefixed = postcss.decl({
  prop: '-moz-' + decl.prop,
  value: decl.value
})

// Good
const prefixed = decl.clone({ prop: '-moz-' + decl.prop })

if (atrule.name === 'add-link') {
  const rule = postcss.rule({ selector: 'a', source: atrule.source })
  atrule.parent.insertBefore(atrule, rule)
}

Type: Source.

Comment#text

The comment's text.

Type: string.

Comment#type

tring representing the node’s type. Possible values are root, atrule, rule, decl, or comment.

new Declaration({ prop: 'color', value: 'black' }).type //=> 'decl'

Type: "comment".

Comment#after()

Insert new node after current node to current node’s parent.

Just alias for node.parent.insertAfter(node, add).

decl.after('color: black')

Returns default. This node for methods chain.

Comment#assign()

Assigns properties to the current node.

decl.assign({ prop: 'word-wrap', value: 'break-word' })

Returns default.

Comment#before()

Insert new node before current node to current node’s parent.

Just alias for node.parent.insertBefore(node, add).

decl.before('content: ""')

Returns default. This node for methods chain.

Comment#cleanRaws()

Clear the code style properties for the node and its children.

node.raws.before  //=> ' '
node.cleanRaws()
node.raws.before  //=> undefined

Comment#clone()

Returns an exact clone of the node.

The resulting cloned node and its (cloned) children will retain code style properties.

decl.raws.before    //=> "\n  "
const cloned = decl.clone({ prop: '-moz-' + decl.prop })
cloned.raws.before  //=> "\n  "
cloned.toString()   //=> -moz-transform: scale(0)

Returns default.

Comment#cloneAfter()

Shortcut to clone the node and insert the resulting cloned node after the current node.

Returns default.

Comment#cloneBefore()

Shortcut to clone the node and insert the resulting cloned node before the current node.

decl.cloneBefore({ prop: '-moz-' + decl.prop })

Returns default.

Comment#error()

Returns a CssSyntaxError instance containing the original position of the node in the source, showing line and column numbers and also a small excerpt to facilitate debugging.

If present, an input source map will be used to get the original position of the source, even from a previous compilation step (e.g., from Sass compilation).

This method produces very useful error messages.

if (!variables[name]) {
  throw decl.error(`Unknown variable ${name}`, { word: name })
  // CssSyntaxError: postcss-vars:a.sass:4:3: Unknown variable $black
  //   color: $black
  // a
  //          ^
  //   background: white
}

Returns default. Error object to throw it.

Comment#next()

Returns the next child of the node’s parent. Returns undefined if the current node is the last child.

if (comment.text === 'delete next') {
  const next = comment.next()
  if (next) {
    next.remove()
  }
}

Returns ChildNode. Next node.

Comment#positionBy()

Get the position for a word or an index inside the node.

Returns Position. Position.

Comment#positionInside()

Convert string index to line/column.

Returns Position. Symbol position in file.

Comment#prev()

Returns the previous child of the node’s parent. Returns undefined if the current node is the first child.

const annotation = decl.prev()
if (annotation.type === 'comment') {
  readAnnotation(annotation.text)
}

Returns ChildNode. Previous node.

Comment#rangeBy()

Get the range for a word or start and end index inside the node. The start index is inclusive; the end index is exclusive.

Returns Range. Range.

Comment#raw()

Returns a Node#raws value. If the node is missing the code style property (because the node was manually built or cloned), PostCSS will try to autodetect the code style property by looking at other nodes in the tree.

const root = postcss.parse('a { background: white }')
root.nodes[0].append({ prop: 'color', value: 'black' })
root.nodes[0].nodes[1].raws.before   //=> undefined
root.nodes[0].nodes[1].raw('before') //=> ' '

Returns string. Code style value.

Comment#remove()

Removes the node from its parent and cleans the parent properties from the node and its children.

if (decl.prop.match(/^-webkit-/)) {
  decl.remove()
}

Returns default. Node to make calls chain.

Comment#replaceWith()

Inserts node(s) before the current node and removes the current node.

AtRule: {
  mixin: atrule => {
    atrule.replaceWith(mixinRules[atrule.params])
  }
}

Returns default. Current node to methods chain.

Comment#root()

Finds the Root instance of the node’s tree.

root.nodes[0].nodes[0].root() === root

Returns default. Root parent.

Comment#toJSON()

Fix circular links on JSON.stringify().

Returns object. Cleaned object.

Comment#toString()

Returns a CSS string representing the node.

new Rule({ selector: 'a' }).toString() //=> "a {}"

Returns string. CSS string of this node.

Comment#warn()

This method is provided as a convenience wrapper for Result#warn.

  Declaration: {
    bad: (decl, { result }) => {
      decl.warn(result, 'Deprecated property bad')
    }
  }

Returns default. Created warning object.

Container

The Root, AtRule, and Rule container nodes inherit some common methods to help work with their children.

Note that all containers can store any content. If you write a rule inside a rule, PostCSS will parse it.

Container#nodes

An array containing the container’s children.

const root = postcss.parse('a { color: black }')
root.nodes.length           //=> 1
root.nodes[0].selector      //=> 'a'
root.nodes[0].nodes[0].prop //=> 'color'

Type: Child[].

Container#parent

The node’s parent node.

root.nodes[0].parent === root

Type: default<ChildNode> | default.

Container#raws

Information to generate byte-to-byte equal node string as it was in the origin input.

Every parser saves its own properties, but the default CSS parser uses:

• before: the space symbols before the node. It also stores * and _ symbols before the declaration (IE hack).
• after: the space symbols after the last child of the node to the end of the node.
• between: the symbols between the property and value for declarations, selector and { for rules, or last parameter and { for at-rules.
• semicolon: contains true if the last child has an (optional) semicolon.
• afterName: the space between the at-rule name and its parameters.
• left: the space symbols between /* and the comment’s text.
• right: the space symbols between the comment’s text and */.
• important: the content of the important statement, if it is not just !important.

PostCSS cleans selectors, declaration values and at-rule parameters from comments and extra spaces, but it stores origin content in raws properties. As such, if you don’t change a declaration’s value, PostCSS will use the raw value with comments.

const root = postcss.parse('a {\n  color:black\n}')
root.first.first.raws //=> { before: '\n  ', between: ':' }

Type: any.

Container#source

The input source of the node.

The property is used in source map generation.

If you create a node manually (e.g., with postcss.decl()), that node will not have a source property and will be absent from the source map. For this reason, the plugin developer should consider cloning nodes to create new ones (in which case the new node’s source will reference the original, cloned node) or setting the source property manually.

decl.source.input.from //=> '/home/ai/a.sass'
decl.source.start      //=> { line: 10, column: 2 }
decl.source.end        //=> { line: 10, column: 12 }

// Bad
const prefixed = postcss.decl({
  prop: '-moz-' + decl.prop,
  value: decl.value
})

// Good
const prefixed = decl.clone({ prop: '-moz-' + decl.prop })

if (atrule.name === 'add-link') {
  const rule = postcss.rule({ selector: 'a', source: atrule.source })
  atrule.parent.insertBefore(atrule, rule)
}

Type: Source.

Container#type

tring representing the node’s type. Possible values are root, atrule, rule, decl, or comment.

new Declaration({ prop: 'color', value: 'black' }).type //=> 'decl'

Type: string.

Container#first

The container’s first child.

rule.first === rules.nodes[0]

Container#last

The container’s last child.

rule.last === rule.nodes[rule.nodes.length - 1]

Container#after()

Insert new node after current node to current node’s parent.

Just alias for node.parent.insertAfter(node, add).

decl.after('color: black')

Returns default<Child>. This node for methods chain.

Container#append()

Inserts new nodes to the end of the container.

const decl1 = new Declaration({ prop: 'color', value: 'black' })
const decl2 = new Declaration({ prop: 'background-color', value: 'white' })
rule.append(decl1, decl2)

root.append({ name: 'charset', params: '"UTF-8"' })  // at-rule
root.append({ selector: 'a' })                       // rule
rule.append({ prop: 'color', value: 'black' })       // declaration
rule.append({ text: 'Comment' })                     // comment

root.append('a {}')
root.first.append('color: black; z-index: 1')

Returns default<Child>. This node for methods chain.

Container#assign()

Assigns properties to the current node.

decl.assign({ prop: 'word-wrap', value: 'break-word' })

Returns default<Child>. Current node to methods chain.

Container#before()

Insert new node before current node to current node’s parent.

Just alias for node.parent.insertBefore(node, add).

decl.before('content: ""')

Returns default<Child>. This node for methods chain.

Container#cleanRaws()

Clear the code style properties for the node and its children.

node.raws.before  //=> ' '
node.cleanRaws()
node.raws.before  //=> undefined

Container#clone()

Returns an exact clone of the node.

The resulting cloned node and its (cloned) children will retain code style properties.

decl.raws.before    //=> "\n  "
const cloned = decl.clone({ prop: '-moz-' + decl.prop })
cloned.raws.before  //=> "\n  "
cloned.toString()   //=> -moz-transform: scale(0)

Returns default<Child>. Clone of the node.

Container#cloneAfter()

Shortcut to clone the node and insert the resulting cloned node after the current node.

Returns default<Child>. New node.

Container#cloneBefore()

Shortcut to clone the node and insert the resulting cloned node before the current node.

decl.cloneBefore({ prop: '-moz-' + decl.prop })

Returns default<Child>. New node

Container#each()

Iterates through the container’s immediate children, calling callback for each child.

Returning false in the callback will break iteration.

This method only iterates through the container’s immediate children. If you need to recursively iterate through all the container’s descendant nodes, use Container#walk.

Unlike the for {}-cycle or Array#forEach this iterator is safe if you are mutating the array of child nodes during iteration. PostCSS will adjust the current index to match the mutations.

const root = postcss.parse('a { color: black; z-index: 1 }')
const rule = root.first

for (const decl of rule.nodes) {
  decl.cloneBefore({ prop: '-webkit-' + decl.prop })
  // Cycle will be infinite, because cloneBefore moves the current node
  // to the next index
}

rule.each(decl => {
  decl.cloneBefore({ prop: '-webkit-' + decl.prop })
  // Will be executed only for color and z-index
})

Returns void | false. Returns false if iteration was broke.

Container#error()

Returns a CssSyntaxError instance containing the original position of the node in the source, showing line and column numbers and also a small excerpt to facilitate debugging.

If present, an input source map will be used to get the original position of the source, even from a previous compilation step (e.g., from Sass compilation).

This method produces very useful error messages.

if (!variables[name]) {
  throw decl.error(`Unknown variable ${name}`, { word: name })
  // CssSyntaxError: postcss-vars:a.sass:4:3: Unknown variable $black
  //   color: $black
  // a
  //          ^
  //   background: white
}

Returns default. Error object to throw it.

Container#every()

Returns true if callback returns true for all of the container’s children.

const noPrefixes = rule.every(i => i.prop[0] !== '-')

Returns boolean. Is every child pass condition.

Container#index()

Returns a child’s index within the Container#nodes array.

rule.index( rule.nodes[2] ) //=> 2

Returns number. Child index.

Container#insertAfter()

Insert new node after old node within the container.

Returns default<Child>. This node for methods chain.

Container#insertBefore()

Insert new node before old node within the container.

rule.insertBefore(decl, decl.clone({ prop: '-webkit-' + decl.prop }))

Returns default<Child>. This node for methods chain.

Container#next()

Returns the next child of the node’s parent. Returns undefined if the current node is the last child.

if (comment.text === 'delete next') {
  const next = comment.next()
  if (next) {
    next.remove()
  }
}

Returns ChildNode. Next node.

Container#positionBy()

Get the position for a word or an index inside the node.

Returns Position. Position.

Container#positionInside()

Convert string index to line/column.

Returns Position. Symbol position in file.

Container#prepend()

Inserts new nodes to the start of the container.

const decl1 = new Declaration({ prop: 'color', value: 'black' })
const decl2 = new Declaration({ prop: 'background-color', value: 'white' })
rule.prepend(decl1, decl2)

root.append({ name: 'charset', params: '"UTF-8"' })  // at-rule
root.append({ selector: 'a' })                       // rule
rule.append({ prop: 'color', value: 'black' })       // declaration
rule.append({ text: 'Comment' })                     // comment

root.append('a {}')
root.first.append('color: black; z-index: 1')

Returns default<Child>. This node for methods chain.

Container#prev()

Returns the previous child of the node’s parent. Returns undefined if the current node is the first child.

const annotation = decl.prev()
if (annotation.type === 'comment') {
  readAnnotation(annotation.text)
}

Returns ChildNode. Previous node.

Container#push()

Add child to the end of the node.

rule.push(new Declaration({ prop: 'color', value: 'black' }))

Returns default<Child>. This node for methods chain.

Container#rangeBy()

Get the range for a word or start and end index inside the node. The start index is inclusive; the end index is exclusive.

Returns Range. Range.

Container#raw()

Returns a Node#raws value. If the node is missing the code style property (because the node was manually built or cloned), PostCSS will try to autodetect the code style property by looking at other nodes in the tree.

const root = postcss.parse('a { background: white }')
root.nodes[0].append({ prop: 'color', value: 'black' })
root.nodes[0].nodes[1].raws.before   //=> undefined
root.nodes[0].nodes[1].raw('before') //=> ' '

Returns string. Code style value.

Container#remove()

Removes the node from its parent and cleans the parent properties from the node and its children.

if (decl.prop.match(/^-webkit-/)) {
  decl.remove()
}

Returns default<Child>. Node to make calls chain.

Container#removeAll()

Removes all children from the container and cleans their parent properties.

rule.removeAll()
rule.nodes.length //=> 0

Returns default<Child>. This node for methods chain.

Container#removeChild()

Removes node from the container and cleans the parent properties from the node and its children.

rule.nodes.length  //=> 5
rule.removeChild(decl)
rule.nodes.length  //=> 4
decl.parent        //=> undefined

Returns default<Child>. This node for methods chain.

Container#replaceValues()

Passes all declaration values within the container that match pattern through callback, replacing those values with the returned result of callback.

This method is useful if you are using a custom unit or function and need to iterate through all values.

root.replaceValues(/\d+rem/, { fast: 'rem' }, string => {
  return 15 * parseInt(string) + 'px'
})

Returns default<Child>. This node for methods chain.

Container#replaceWith()

Inserts node(s) before the current node and removes the current node.

AtRule: {
  mixin: atrule => {
    atrule.replaceWith(mixinRules[atrule.params])
  }
}

Returns default<Child>. Current node to methods chain.

Container#root()

Finds the Root instance of the node’s tree.

root.nodes[0].nodes[0].root() === root

Returns default. Root parent.

Container#some()

Returns true if callback returns true for (at least) one of the container’s children.

const hasPrefix = rule.some(i => i.prop[0] === '-')

Returns boolean. Is some child pass condition.

Container#toJSON()

Fix circular links on JSON.stringify().

Returns object. Cleaned object.

Container#toString()

Returns a CSS string representing the node.

new Rule({ selector: 'a' }).toString() //=> "a {}"

Returns string. CSS string of this node.

Container#walk()

Traverses the container’s descendant nodes, calling callback for each node.

Like container.each(), this method is safe to use if you are mutating arrays during iteration.

If you only need to iterate through the container’s immediate children, use Container#each.

root.walk(node => {
  // Traverses all descendant nodes.
})

Returns void | false. Returns false if iteration was broke.

Container#walkAtRules()

Traverses the container’s descendant nodes, calling callback for each at-rule node.

If you pass a filter, iteration will only happen over at-rules that have matching names.

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

root.walkAtRules(rule => {
  if (isOld(rule.name)) rule.remove()
})

let first = false
root.walkAtRules('charset', rule => {
  if (!first) {
    first = true
  } else {
    rule.remove()
  }
})

Returns void | false. Returns false if iteration was broke.

Container#walkComments()

Traverses the container’s descendant nodes, calling callback for each comment node.

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

root.walkComments(comment => {
  comment.remove()
})

Returns void | false. Returns false if iteration was broke.

Container#walkDecls()

Traverses the container’s descendant nodes, calling callback for each declaration node.

If you pass a filter, iteration will only happen over declarations with matching properties.

root.walkDecls(decl => {
  checkPropertySupport(decl.prop)
})

root.walkDecls('border-radius', decl => {
  decl.remove()
})

root.walkDecls(/^background/, decl => {
  decl.value = takeFirstColorFromGradient(decl.value)
})

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

Returns void | false. Returns false if iteration was broke.

Container#walkRules()

Traverses the container’s descendant nodes, calling callback for each rule node.

If you pass a filter, iteration will only happen over rules with matching selectors.

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

const selectors = []
root.walkRules(rule => {
  selectors.push(rule.selector)
})
console.log(`Your CSS uses ${ selectors.length } selectors`)

Returns void | false. Returns false if iteration was broke.

Container#warn()

This method is provided as a convenience wrapper for Result#warn.

  Declaration: {
    bad: (decl, { result }) => {
      decl.warn(result, 'Deprecated property bad')
    }
  }

Returns default. Created warning object.

CssSyntaxError

The CSS parser throws this error for broken CSS.

Custom parsers can throw this error for broken custom syntax using the Node#error method.

PostCSS will use the input source map to detect the original error location. If you wrote a Sass file, compiled it to CSS and then parsed it with PostCSS, PostCSS will show the original position in the Sass file.

If you need the position in the PostCSS input (e.g., to debug the previous compiler), use error.input.file.

// Raising error from plugin
throw node.error('Unknown variable', { plugin: 'postcss-vars' })

// Catching and checking syntax error
try {
  postcss.parse('a{')
} catch (error) {
  if (error.name === 'CssSyntaxError') {
    error //=> CssSyntaxError
  }
}

CssSyntaxError#column

Source column of the error.

error.column       //=> 1
error.input.column //=> 4

PostCSS will use the input source map to detect the original location. If you need the position in the PostCSS input, use error.input.column.

Type: number.

CssSyntaxError#endColumn

Source column of the error's end, exclusive. Provided if the error pertains to a range.

error.endColumn       //=> 1
error.input.endColumn //=> 4

PostCSS will use the input source map to detect the original location. If you need the position in the PostCSS input, use error.input.endColumn.

Type: number.

CssSyntaxError#endLine

Source line of the error's end, exclusive. Provided if the error pertains to a range.

error.endLine       //=> 3
error.input.endLine //=> 4

PostCSS will use the input source map to detect the original location. If you need the position in the PostCSS input, use error.input.endLine.

Type: number.

CssSyntaxError#file

Absolute path to the broken file.

error.file       //=> 'a.sass'
error.input.file //=> 'a.css'

PostCSS will use the input source map to detect the original location. If you need the position in the PostCSS input, use error.input.file.

Type: string.

CssSyntaxError#input

Input object with PostCSS internal information about input file. If input has source map from previous tool, PostCSS will use origin (for example, Sass) source. You can use this object to get PostCSS input source.

error.input.file //=> 'a.css'
error.file       //=> 'a.sass'

Type: FilePosition.

CssSyntaxError#line

Source line of the error.

error.line       //=> 2
error.input.line //=> 4

PostCSS will use the input source map to detect the original location. If you need the position in the PostCSS input, use error.input.line.

Type: number.

CssSyntaxError#message

Full error text in the GNU error format with plugin, file, line and column.

error.message //=> 'a.css:1:1: Unclosed block'

Type: string.

CssSyntaxError#name

Always equal to 'CssSyntaxError'. You should always check error type by error.name === 'CssSyntaxError' instead of error instanceof CssSyntaxError, because npm could have several PostCSS versions.

if (error.name === 'CssSyntaxError') {
  error //=> CssSyntaxError
}

Type: "CssSyntaxError".

CssSyntaxError#plugin

Plugin name, if error came from plugin.

error.plugin //=> 'postcss-vars'

Type: string.

CssSyntaxError#reason

Error message.

error.message //=> 'Unclosed block'

Type: string.

CssSyntaxError#source

Source code of the broken file.

error.source       //=> 'a { b {} }'
error.input.source //=> 'a b { }'

Type: string.

CssSyntaxError#stack

Type: string.

CssSyntaxError#showSourceCode()

Returns a few lines of CSS source that caused the error.

If the CSS has an input source map without sourceContent, this method will return an empty string.

error.showSourceCode() //=> "  4 | }
                       //      5 | a {
                       //    > 6 |   bad
                       //        |   ^
                       //      7 | }
                       //      8 | b {"

Returns string. Few lines of CSS source that caused the error.

CssSyntaxError#toString()

Returns error position, message and source code of the broken part.

error.toString() //=> "CssSyntaxError: app.css:1:1: Unclosed block
                 //    > 1 | a {
                 //        | ^"

Returns string. Error position, message and source code.

Declaration

Represents a CSS declaration.

Once (root, { Declaration }) {
  let color = new Declaration({ prop: 'color', value: 'black' })
  root.append(color)
}

const root = postcss.parse('a { color: black }')
const decl = root.first.first
decl.type       //=> 'decl'
decl.toString() //=> ' color: black'

Declaration#important

true if the declaration has an !important annotation.

const root = postcss.parse('a { color: black !important; color: red }')
root.first.first.important //=> true
root.first.last.important  //=> undefined

Type: boolean.

Declaration#parent

The node’s parent node.

root.nodes[0].parent === root

Type: default<ChildNode>.

Declaration#prop

The declaration's property name.

const root = postcss.parse('a { color: black }')
const decl = root.first.first
decl.prop //=> 'color'

Type: string.

Declaration#raws

Information to generate byte-to-byte equal node string as it was in the origin input.

Every parser saves its own properties, but the default CSS parser uses:

• before: the space symbols before the node. It also stores * and _ symbols before the declaration (IE hack).
• after: the space symbols after the last child of the node to the end of the node.
• between: the symbols between the property and value for declarations, selector and { for rules, or last parameter and { for at-rules.
• semicolon: contains true if the last child has an (optional) semicolon.
• afterName: the space between the at-rule name and its parameters.
• left: the space symbols between /* and the comment’s text.
• right: the space symbols between the comment’s text and */.
• important: the content of the important statement, if it is not just !important.

PostCSS cleans selectors, declaration values and at-rule parameters from comments and extra spaces, but it stores origin content in raws properties. As such, if you don’t change a declaration’s value, PostCSS will use the raw value with comments.

const root = postcss.parse('a {\n  color:black\n}')
root.first.first.raws //=> { before: '\n  ', between: ':' }

Type: DeclarationRaws.

Declaration#source

The input source of the node.

The property is used in source map generation.

If you create a node manually (e.g., with postcss.decl()), that node will not have a source property and will be absent from the source map. For this reason, the plugin developer should consider cloning nodes to create new ones (in which case the new node’s source will reference the original, cloned node) or setting the source property manually.

decl.source.input.from //=> '/home/ai/a.sass'
decl.source.start      //=> { line: 10, column: 2 }
decl.source.end        //=> { line: 10, column: 12 }

// Bad
const prefixed = postcss.decl({
  prop: '-moz-' + decl.prop,
  value: decl.value
})

// Good
const prefixed = decl.clone({ prop: '-moz-' + decl.prop })

if (atrule.name === 'add-link') {
  const rule = postcss.rule({ selector: 'a', source: atrule.source })
  atrule.parent.insertBefore(atrule, rule)
}

Type: Source.

Declaration#type

tring representing the node’s type. Possible values are root, atrule, rule, decl, or comment.

new Declaration({ prop: 'color', value: 'black' }).type //=> 'decl'

Type: "decl".

Declaration#value

The declaration’s value.

This value will be cleaned of comments. If the source value contained comments, those comments will be available in the raws property. If you have not changed the value, the result of decl.toString() will include the original raws value (comments and all).

const root = postcss.parse('a { color: black }')
const decl = root.first.first
decl.value //=> 'black'

Type: string.

Declaration#variable

true if declaration is declaration of CSS Custom Property or Sass variable.

const root = postcss.parse(':root { --one: 1 }')
let one = root.first.first
one.variable //=> true

const root = postcss.parse('$one: 1')
let one = root.first
one.variable //=> true

Type: boolean.

Declaration#after()

Insert new node after current node to current node’s parent.

Just alias for node.parent.insertAfter(node, add).

decl.after('color: black')

Returns default. This node for methods chain.

Declaration#assign()

Assigns properties to the current node.

decl.assign({ prop: 'word-wrap', value: 'break-word' })

Returns default.

Declaration#before()

Insert new node before current node to current node’s parent.

Just alias for node.parent.insertBefore(node, add).

decl.before('content: ""')

Returns default. This node for methods chain.

Declaration#cleanRaws()

Clear the code style properties for the node and its children.

node.raws.before  //=> ' '
node.cleanRaws()
node.raws.before  //=> undefined

Declaration#clone()

Returns an exact clone of the node.

The resulting cloned node and its (cloned) children will retain code style properties.

decl.raws.before    //=> "\n  "
const cloned = decl.clone({ prop: '-moz-' + decl.prop })
cloned.raws.before  //=> "\n  "
cloned.toString()   //=> -moz-transform: scale(0)

Returns default.

Declaration#cloneAfter()

Shortcut to clone the node and insert the resulting cloned node after the current node.

Returns default.

Declaration#cloneBefore()

Shortcut to clone the node and insert the resulting cloned node before the current node.

decl.cloneBefore({ prop: '-moz-' + decl.prop })

Returns default.

Declaration#error()

Returns a CssSyntaxError instance containing the original position of the node in the source, showing line and column numbers and also a small excerpt to facilitate debugging.

If present, an input source map will be used to get the original position of the source, even from a previous compilation step (e.g., from Sass compilation).

This method produces very useful error messages.

if (!variables[name]) {
  throw decl.error(`Unknown variable ${name}`, { word: name })
  // CssSyntaxError: postcss-vars:a.sass:4:3: Unknown variable $black
  //   color: $black
  // a
  //          ^
  //   background: white
}

Returns default. Error object to throw it.

Declaration#next()

Returns the next child of the node’s parent. Returns undefined if the current node is the last child.

if (comment.text === 'delete next') {
  const next = comment.next()
  if (next) {
    next.remove()
  }
}

Returns ChildNode. Next node.

Declaration#positionBy()

Get the position for a word or an index inside the node.

Returns Position. Position.

Declaration#positionInside()

Convert string index to line/column.

Returns Position. Symbol position in file.

Declaration#prev()

Returns the previous child of the node’s parent. Returns undefined if the current node is the first child.

const annotation = decl.prev()
if (annotation.type === 'comment') {
  readAnnotation(annotation.text)
}

Returns ChildNode. Previous node.

Declaration#rangeBy()

Get the range for a word or start and end index inside the node. The start index is inclusive; the end index is exclusive.

Returns Range. Range.

Declaration#raw()

Returns a Node#raws value. If the node is missing the code style property (because the node was manually built or cloned), PostCSS will try to autodetect the code style property by looking at other nodes in the tree.

const root = postcss.parse('a { background: white }')
root.nodes[0].append({ prop: 'color', value: 'black' })
root.nodes[0].nodes[1].raws.before   //=> undefined
root.nodes[0].nodes[1].raw('before') //=> ' '

Returns string. Code style value.

Declaration#remove()

Removes the node from its parent and cleans the parent properties from the node and its children.

if (decl.prop.match(/^-webkit-/)) {
  decl.remove()
}

Returns default. Node to make calls chain.

Declaration#replaceWith()

Inserts node(s) before the current node and removes the current node.

AtRule: {
  mixin: atrule => {
    atrule.replaceWith(mixinRules[atrule.params])
  }
}

Returns default. Current node to methods chain.

Declaration#root()

Finds the Root instance of the node’s tree.

root.nodes[0].nodes[0].root() === root

Returns default. Root parent.

Declaration#toJSON()

Fix circular links on JSON.stringify().

Returns object. Cleaned object.

Declaration#toString()

Returns a CSS string representing the node.

new Rule({ selector: 'a' }).toString() //=> "a {}"

Returns string. CSS string of this node.

Declaration#warn()

This method is provided as a convenience wrapper for Result#warn.

  Declaration: {
    bad: (decl, { result }) => {
      decl.warn(result, 'Deprecated property bad')
    }
  }

Returns default. Created warning object.

Document

Represents a file and contains all its parsed nodes.

Experimental: some aspects of this node could change within minor or patch version releases.

const document = htmlParser(
  '<html><style>a{color:black}</style><style>b{z-index:2}</style>'
)
document.type         //=> 'document'
document.nodes.length //=> 2

Document#nodes

An array containing the container’s children.

const root = postcss.parse('a { color: black }')
root.nodes.length           //=> 1
root.nodes[0].selector      //=> 'a'
root.nodes[0].nodes[0].prop //=> 'color'

Type: default[].

Document#parent

The node’s parent node.

root.nodes[0].parent === root

Type: undefined.

Document#raws

Information to generate byte-to-byte equal node string as it was in the origin input.

Every parser saves its own properties, but the default CSS parser uses:

• before: the space symbols before the node. It also stores * and _ symbols before the declaration (IE hack).
• after: the space symbols after the last child of the node to the end of the node.
• between: the symbols between the property and value for declarations, selector and { for rules, or last parameter and { for at-rules.
• semicolon: contains true if the last child has an (optional) semicolon.
• afterName: the space between the at-rule name and its parameters.
• left: the space symbols between /* and the comment’s text.
• right: the space symbols between the comment’s text and */.
• important: the content of the important statement, if it is not just !important.

PostCSS cleans selectors, declaration values and at-rule parameters from comments and extra spaces, but it stores origin content in raws properties. As such, if you don’t change a declaration’s value, PostCSS will use the raw value with comments.

const root = postcss.parse('a {\n  color:black\n}')
root.first.first.raws //=> { before: '\n  ', between: ':' }

Type: any.

Document#source

The input source of the node.

The property is used in source map generation.

If you create a node manually (e.g., with postcss.decl()), that node will not have a source property and will be absent from the source map. For this reason, the plugin developer should consider cloning nodes to create new ones (in which case the new node’s source will reference the original, cloned node) or setting the source property manually.

decl.source.input.from //=> '/home/ai/a.sass'
decl.source.start      //=> { line: 10, column: 2 }
decl.source.end        //=> { line: 10, column: 12 }

// Bad
const prefixed = postcss.decl({
  prop: '-moz-' + decl.prop,
  value: decl.value
})

// Good
const prefixed = decl.clone({ prop: '-moz-' + decl.prop })

if (atrule.name === 'add-link') {
  const rule = postcss.rule({ selector: 'a', source: atrule.source })
  atrule.parent.insertBefore(atrule, rule)
}

Type: Source.

Document#type

tring representing the node’s type. Possible values are root, atrule, rule, decl, or comment.

new Declaration({ prop: 'color', value: 'black' }).type //=> 'decl'

Type: "document".

Document#first

The container’s first child.

rule.first === rules.nodes[0]

Document#last

The container’s last child.

rule.last === rule.nodes[rule.nodes.length - 1]

Document#after()

Insert new node after current node to current node’s parent.

Just alias for node.parent.insertAfter(node, add).

decl.after('color: black')

Returns default. This node for methods chain.

Document#append()

Inserts new nodes to the end of the container.

const decl1 = new Declaration({ prop: 'color', value: 'black' })
const decl2 = new Declaration({ prop: 'background-color', value: 'white' })
rule.append(decl1, decl2)

root.append({ name: 'charset', params: '"UTF-8"' })  // at-rule
root.append({ selector: 'a' })                       // rule
rule.append({ prop: 'color', value: 'black' })       // declaration
rule.append({ text: 'Comment' })                     // comment

root.append('a {}')
root.first.append('color: black; z-index: 1')

Returns default. This node for methods chain.

Document#assign()

Assigns properties to the current node.

decl.assign({ prop: 'word-wrap', value: 'break-word' })

Returns default. Current node to methods chain.

Document#before()

Insert new node before current node to current node’s parent.

Just alias for node.parent.insertBefore(node, add).

decl.before('content: ""')

Returns default. This node for methods chain.

Document#cleanRaws()

Clear the code style properties for the node and its children.

node.raws.before  //=> ' '
node.cleanRaws()
node.raws.before  //=> undefined

Document#clone()

Returns an exact clone of the node.

The resulting cloned node and its (cloned) children will retain code style properties.

decl.raws.before    //=> "\n  "
const cloned = decl.clone({ prop: '-moz-' + decl.prop })
cloned.raws.before  //=> "\n  "
cloned.toString()   //=> -moz-transform: scale(0)

Returns default. Clone of the node.

Document#cloneAfter()

Shortcut to clone the node and insert the resulting cloned node after the current node.

Returns default. New node.

Document#cloneBefore()

Shortcut to clone the node and insert the resulting cloned node before the current node.

decl.cloneBefore({ prop: '-moz-' + decl.prop })

Returns default. New node

Document#each()

Iterates through the container’s immediate children, calling callback for each child.

Returning false in the callback will break iteration.

This method only iterates through the container’s immediate children. If you need to recursively iterate through all the container’s descendant nodes, use Container#walk.

Unlike the for {}-cycle or Array#forEach this iterator is safe if you are mutating the array of child nodes during iteration. PostCSS will adjust the current index to match the mutations.

const root = postcss.parse('a { color: black; z-index: 1 }')
const rule = root.first

for (const decl of rule.nodes) {
  decl.cloneBefore({ prop: '-webkit-' + decl.prop })
  // Cycle will be infinite, because cloneBefore moves the current node
  // to the next index
}

rule.each(decl => {
  decl.cloneBefore({ prop: '-webkit-' + decl.prop })
  // Will be executed only for color and z-index
})

Returns void | false. Returns false if iteration was broke.

Document#error()

Returns a CssSyntaxError instance containing the original position of the node in the source, showing line and column numbers and also a small excerpt to facilitate debugging.

If present, an input source map will be used to get the original position of the source, even from a previous compilation step (e.g., from Sass compilation).

This method produces very useful error messages.

if (!variables[name]) {
  throw decl.error(`Unknown variable ${name}`, { word: name })
  // CssSyntaxError: postcss-vars:a.sass:4:3: Unknown variable $black
  //   color: $black
  // a
  //          ^
  //   background: white
}

Returns default. Error object to throw it.

Document#every()

Returns true if callback returns true for all of the container’s children.

const noPrefixes = rule.every(i => i.prop[0] !== '-')

Returns boolean. Is every child pass condition.

Document#index()

Returns a child’s index within the Container#nodes array.

rule.index( rule.nodes[2] ) //=> 2

Returns number. Child index.

Document#insertAfter()

Insert new node after old node within the container.

Returns default. This node for methods chain.

Document#insertBefore()

Insert new node before old node within the container.

rule.insertBefore(decl, decl.clone({ prop: '-webkit-' + decl.prop }))

Returns default. This node for methods chain.

Document#next()

Returns the next child of the node’s parent. Returns undefined if the current node is the last child.

if (comment.text === 'delete next') {
  const next = comment.next()
  if (next) {
    next.remove()
  }
}

Returns ChildNode. Next node.

Document#positionBy()

Get the position for a word or an index inside the node.

Returns Position. Position.

Document#positionInside()

Convert string index to line/column.

Returns Position. Symbol position in file.

Document#prepend()

Inserts new nodes to the start of the container.

const decl1 = new Declaration({ prop: 'color', value: 'black' })
const decl2 = new Declaration({ prop: 'background-color', value: 'white' })
rule.prepend(decl1, decl2)

root.append({ name: 'charset', params: '"UTF-8"' })  // at-rule
root.append({ selector: 'a' })                       // rule
rule.append({ prop: 'color', value: 'black' })       // declaration
rule.append({ text: 'Comment' })                     // comment

root.append('a {}')
root.first.append('color: black; z-index: 1')

Returns default. This node for methods chain.

Document#prev()

Returns the previous child of the node’s parent. Returns undefined if the current node is the first child.

const annotation = decl.prev()
if (annotation.type === 'comment') {
  readAnnotation(annotation.text)
}

Returns ChildNode. Previous node.

Document#push()

Add child to the end of the node.

rule.push(new Declaration({ prop: 'color', value: 'black' }))

Returns default. This node for methods chain.

Document#rangeBy()

Get the range for a word or start and end index inside the node. The start index is inclusive; the end index is exclusive.

Returns Range. Range.

Document#raw()

Returns a Node#raws value. If the node is missing the code style property (because the node was manually built or cloned), PostCSS will try to autodetect the code style property by looking at other nodes in the tree.

const root = postcss.parse('a { background: white }')
root.nodes[0].append({ prop: 'color', value: 'black' })
root.nodes[0].nodes[1].raws.before   //=> undefined
root.nodes[0].nodes[1].raw('before') //=> ' '

Returns string. Code style value.

Document#remove()

Removes the node from its parent and cleans the parent properties from the node and its children.

if (decl.prop.match(/^-webkit-/)) {
  decl.remove()
}

Returns default. Node to make calls chain.

Document#removeAll()

Removes all children from the container and cleans their parent properties.

rule.removeAll()
rule.nodes.length //=> 0

Returns default. This node for methods chain.

Document#removeChild()

Removes node from the container and cleans the parent properties from the node and its children.

rule.nodes.length  //=> 5
rule.removeChild(decl)
rule.nodes.length  //=> 4
decl.parent        //=> undefined

Returns default. This node for methods chain.

Document#replaceValues()

Passes all declaration values within the container that match pattern through callback, replacing those values with the returned result of callback.

This method is useful if you are using a custom unit or function and need to iterate through all values.

root.replaceValues(/\d+rem/, { fast: 'rem' }, string => {
  return 15 * parseInt(string) + 'px'
})

Returns default. This node for methods chain.

Document#replaceWith()

Inserts node(s) before the current node and removes the current node.

AtRule: {
  mixin: atrule => {
    atrule.replaceWith(mixinRules[atrule.params])
  }
}

Returns default. Current node to methods chain.

Document#root()

Finds the Root instance of the node’s tree.

root.nodes[0].nodes[0].root() === root

Returns default. Root parent.

Document#some()

Returns true if callback returns true for (at least) one of the container’s children.

const hasPrefix = rule.some(i => i.prop[0] === '-')

Returns boolean. Is some child pass condition.

Document#toJSON()

Fix circular links on JSON.stringify().

Returns object. Cleaned object.

Document#toResult()

Returns a Result instance representing the document’s CSS roots.

const root1 = postcss.parse(css1, { from: 'a.css' })
const root2 = postcss.parse(css2, { from: 'b.css' })
const document = postcss.document()
document.append(root1)
document.append(root2)
const result = document.toResult({ to: 'all.css', map: true })

Returns default. Result with current document’s CSS.

Document#toString()

Returns a CSS string representing the node.

new Rule({ selector: 'a' }).toString() //=> "a {}"

Returns string. CSS string of this node.

Document#walk()

Traverses the container’s descendant nodes, calling callback for each node.

Like container.each(), this method is safe to use if you are mutating arrays during iteration.

If you only need to iterate through the container’s immediate children, use Container#each.

root.walk(node => {
  // Traverses all descendant nodes.
})

Returns void | false. Returns false if iteration was broke.

Document#walkAtRules()

Traverses the container’s descendant nodes, calling callback for each at-rule node.

If you pass a filter, iteration will only happen over at-rules that have matching names.

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

root.walkAtRules(rule => {
  if (isOld(rule.name)) rule.remove()
})

let first = false
root.walkAtRules('charset', rule => {
  if (!first) {
    first = true
  } else {
    rule.remove()
  }
})

Returns void | false. Returns false if iteration was broke.

Document#walkComments()

Traverses the container’s descendant nodes, calling callback for each comment node.

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

root.walkComments(comment => {
  comment.remove()
})

Returns void | false. Returns false if iteration was broke.

Document#walkDecls()

Traverses the container’s descendant nodes, calling callback for each declaration node.

If you pass a filter, iteration will only happen over declarations with matching properties.

root.walkDecls(decl => {
  checkPropertySupport(decl.prop)
})

root.walkDecls('border-radius', decl => {
  decl.remove()
})

root.walkDecls(/^background/, decl => {
  decl.value = takeFirstColorFromGradient(decl.value)
})

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

Returns void | false. Returns false if iteration was broke.

Document#walkRules()

Traverses the container’s descendant nodes, calling callback for each rule node.

If you pass a filter, iteration will only happen over rules with matching selectors.

Like Container#each, this method is safe to use if you are mutating arrays during iteration.

const selectors = []
root.walkRules(rule => {
  selectors.push(rule.selector)
})
console.log(`Your CSS uses ${ selectors.length } selectors`)

Returns void | false. Returns false if iteration was broke.

Document#warn()

This method is provided as a convenience wrapper for Result#warn.

  Declaration: {
    bad: (decl, { result }) => {
      decl.warn(result, 'Deprecated property bad')
    }
  }

Returns default. Created warning object.

Input

Represents the source CSS.

const root  = postcss.parse(css, { from: file })
const input = root.source.input

Input#css

Input CSS source.

const input = postcss.parse('a{}', { from: file }).input
input.css //=> "a{}"

Type: string.

Input#file

The absolute path to the CSS source file defined with the from option.

const root = postcss.parse(css, { from: 'a.css' })
root.source.input.file //=> '/home/ai/a.css'

Type: string.

Input#hasBOM

The flag to indicate whether or not the source code has Unicode BOM.

Type: boolean.

Input#id

The unique ID of the CSS source. It will be created if from option is not provided (because PostCSS does not know the file path).

const root = postcss.parse(css)
root.source.input.file //=> undefined
root.source.input.id   //=> "<input css 8LZeVF>"

Type: string.

Input#map

The input source map passed from a compilation step before PostCSS (for example, from Sass compiler).

root.source.input.map.consumer().sources //=> ['a.sass']

Type: default.

Input#from

The CSS source identifier. Contains Input#file if the user set the from option, or Input#id if they did not.

const root = postcss.parse(css, { from: 'a.css' })
root.source.input.from //=> "/home/ai/a.css"

const root = postcss.parse(css)
root.source.input.from //=> "<input css 1>"

Input#fromOffset()

Converts source offset to line and column.

Returns { col: number, line: number }.

Input#origin()

Reads the input source map and returns a symbol position in the input source (e.g., in a Sass file that was compiled to CSS before being passed to PostCSS). Optionally takes an end position, exclusive.

root.source.input.origin(1, 1) //=> { file: 'a.css', line: 3, column: 1 }
root.source.input.origin(1, 1, 1, 4)
//=> { file: 'a.css', line: 3, column: 1, endLine: 3, endColumn: 4 }

Returns false | FilePosition. Position in input source.

LazyResult

A Promise proxy for the result of PostCSS transformations.

A LazyResult instance is returned by Processor#process.

const lazy = postcss([autoprefixer]).process(css)

LazyResult#catch

Processes input CSS through synchronous and asynchronous plugins and calls onRejected for each error thrown in any plugin.

It implements standard Promise API.

postcss([autoprefixer]).process(css).then(result => {
  console.log(result.css)
}).catch(error => {
  console.error(error)
})

Type: (onrejected: (reason: any) => TResult | PromiseLike<TResult>) => Promise<default | TResult>.

LazyResult#finally

Processes input CSS through synchronous and asynchronous plugins and calls onFinally on any error or when all plugins will finish work.

It implements standard Promise API.

postcss([autoprefixer]).process(css).finally(() => {
  console.log('processing ended')
})

Type: (onfinally: () => void) => Promise<default>.

LazyResult#then

Processes input CSS through synchronous and asynchronous plugins and calls onFulfilled with a Result instance. If a plugin throws an error, the onRejected callback will be executed.

It implements standard Promise API.

postcss([autoprefixer]).process(css, { from: cssPath }).then(result => {
  console.log(result.css)
})

Type: (onfulfilled: (value: default) => TResult1 | PromiseLike<TResult1>, onrejected: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>.

LazyResult#[toStringTag]

Returns the default string description of an object. Required to implement the Promise interface.

LazyResult#content

An alias for the css property. Use it with syntaxes that generate non-CSS output.

This property will only work with synchronous plugins. If the processor contains any asynchronous plugins it will throw an error.

PostCSS runners should always use LazyResult#then.

LazyResult#css

Processes input CSS through synchronous plugins, converts Root to a CSS string and returns Result#css.

This property will only work with synchronous plugins. If the processor contains any asynchronous plugins it will throw an error.

PostCSS runners should always use LazyResult#then.

LazyResult#map

Processes input CSS through synchronous plugins and returns Result#map.

This property will only work with synchronous plugins. If the processor contains any asynchronous plugins it will throw an error.

PostCSS runners should always use LazyResult#then.

LazyResult#messages

Processes input CSS through synchronous plugins and returns Result#messages.

This property will only work with synchronous plugins. If the processor contains any asynchronous plugins it will throw an error.

PostCSS runners should always use LazyResult#then.

LazyResult#opts

Options from the Processor#process call.

LazyResult#processor

Returns a Processor instance, which will be used for CSS transformations.

LazyResult#root

Processes input CSS through synchronous plugins and returns Result#root.

This property will only work with synchronous plugins. If the processor contains any asynchronous plugins it will throw an error.

PostCSS runners should always use LazyResult#then.

LazyResult#async()

Run plugin in async way and return Result.

Returns Promise<default>. Result with output content.

LazyResult#sync()

Run plugin in sync way and return Result.

Returns default. Result with output content.

LazyResult#toString()

Alias for the LazyResult#css property.

lazy + '' === lazy.css

Returns string. Output CSS.

LazyResult#warnings()

Processes input CSS through synchronous plugins and calls Result#warnings.

Returns default[]. Warnings from plugins.

NoWorkResult

A Promise proxy for the result of PostCSS transformations. This lazy result instance doesn't parse css unless NoWorkResult#root or Result#root are accessed. See the example below for details. A NoWork instance is returned by Processor#process ONLY when no plugins defined.

const noWorkResult = postcss().process(css) // No plugins are defined.
                                            // CSS is not parsed
let root = noWorkResult.root // now css is parsed because we accessed the root

NoWorkResult#catch

Type: (onrejected: (reason: any) => TResult | PromiseLike<TResult>) => Promise<default | TResult>.

NoWorkResult#finally

Type: (onfinally: () => void) => Promise<default>.

NoWorkResult#then

Type: (onfulfilled: (value: default) => TResult1 | PromiseLike<TResult1>, onrejected: (reason: any) => TResult2 | PromiseLike<TResult2>) => Promise<TResult1 | TResult2>.

NoWorkResult#[toStringTag]

NoWorkResult#content

NoWorkResult#css

NoWorkResult#map

NoWorkResult#messages

NoWorkResult#opts

NoWorkResult#processor

NoWorkResult#root

NoWorkResult#async()

Returns Promise<default>.

NoWorkResult#sync()

Returns default.

NoWorkResult#toString()

Returns string.

NoWorkResult#warnings()

Returns default[].

Node

All node classes inherit the following common methods.

You should not extend this classes to create AST for selector or value parser.

Node#parent

The node’s parent node.

root.nodes[0].parent === root

Type: default<ChildNode> | default.

Node#raws

Information to generate byte-to-byte equal node string as it was in the origin input.

Every parser saves its own properties, but the default CSS parser uses:

• before: the space symbols before the node. It also stores * and _ symbols before the declaration (IE hack).
• after: the space symbols after the last child of the node to the end of the node.
• between: the symbols between the property and value for declarations, selector and { for rules, or last parameter and { for at-rules.
• semicolon: contains true if the last child has an (optional) semicolon.
• afterName: the space between the at-rule name and its parameters.
• left: the space symbols between /* and the comment’s text.
• right: the space symbols between the comment’s text and */.
• important: the content of the important statement, if it is not just !important.

PostCSS cleans selectors, declaration values and at-rule parameters from comments and extra spaces, but it stores origin content in raws properties. As such, if you don’t change a declaration’s value, PostCSS will use the raw value with comments.

const root = postcss.parse('a {\n  color:black\n}')
root.first.first.raws //=> { before: '\n  ', between: ':' }

Type: any.

Node#source

The input source of the node.

The property is used in source map generation.

If you create a node manually (e.g., with postcss.decl()), that node will not have a source property and will be absent from the source map. For this reason, the plugin developer should consider cloning nodes to create new ones (in which case the new node’s source will reference the original, cloned node) or setting the source property manually.

decl.source.input.from //=> '/home/ai/a.sass'
decl.source.start      //=> { line: 10, column: 2 }
decl.source.end        //=> { line: 10, column: 12 }

// Bad
const prefixed = postcss.decl({
  prop: '-moz-' + decl.prop,
  value: decl.value
})

// Good
const prefixed = decl.clone({ prop: '-moz-' + decl.prop })

if (atrule.name === 'add-link') {
  const rule = postcss.rule({ selector: 'a', source: atrule.source })
  atrule.parent.insertBefore(atrule, rule)
}

Type: Source.

Node#type

tring representing the node’s type. Possible values are root, atrule, rule, decl, or comment.

new Declaration({ prop: 'color', value: 'black' }).type //=> 'decl'

Type: string.

Node#after()

Insert new node after current node to current node’s parent.

Just alias for node.parent.insertAfter(node, add).

decl.after('color: black')

Returns default. This node for methods chain.

Node#assign()

Assigns properties to the current node.

decl.assign({ prop: 'word-wrap', value: 'break-word' })

Returns default. Current node to methods chain.

Node#before()

Insert new node before current node to current node’s parent.

Just alias for node.parent.insertBefore(node, add).

decl.before('content: ""')

Returns default. This node for methods chain.

Node#cleanRaws()

Clear the code style properties for the node and its children.

node.raws.before  //=> ' '
node.cleanRaws()
node.raws.before  //=> undefined

Node#clone()

Returns an exact clone of the node.

The resulting cloned node and its (cloned) children will retain code style properties.

decl.raws.before    //=> "\n  "
const cloned = decl.clone({ prop: '-moz-' + decl.prop })
cloned.raws.before  //=> "\n  "
cloned.toString()   //=> -moz-transform: scale(0)

Returns default. Clone of the node.

Node#cloneAfter()

Shortcut to clone the node and insert the resulting cloned node after the current node.

Returns default. New node.

Node#cloneBefore()

Shortcut to clone the node and insert the resulting cloned node before the current node.

decl.cloneBefore({ prop: '-moz-' + decl.prop })

Returns default. New node

Node#error()

Returns a CssSyntaxError instance containing the original position of the node in the source, showing line and column numbers and also a small excerpt to facilitate debugging.

If present, an input source map will be used to get the original position of the source, even from a previous compilation step (e.g., from Sass compilation).

This method produces very useful error messages.

if (!variables[name]) {
  throw decl.error(`Unknown variable ${name}`, { word: name })
  // CssSyntaxError: postcss-vars:a.sass:4:3: Unknown variable $black
  //   color: $black
  // a
  //          ^
  //   background: white
}

Returns default. Error object to throw it.

Node#next()

Returns the next child of the node’s parent. Returns undefined if the current node is the last child.

if (comment.text === 'delete next') {
  const next = comment.next()
  if (next) {
    next.remove()
  }
}

Returns ChildNode. Next node.

Node#positionBy()

Get the position for a word or an index inside the node.

Returns Position. Position.

Node#positionInside()

Convert string index to line/column.

Returns Position. Symbol position in file.

Node#prev()

Returns the previous child of the node’s parent. Returns undefined if the current node is the first child.

const annotation = decl.prev()
if (annotation.type === 'comment') {
  readAnnotation(annotation.text)
}

Returns ChildNode. Previous node.

Node#rangeBy()

Get the range for a word or start and end index inside the node. The start index is inclusive; the end index is exclusive.

Returns Range. Range.

Node#raw()

Returns a Node#raws value. If the node is missing the code style property (because the node was manually built or cloned), PostCSS will try to autodetect the code style property by looking at other nodes in the tree.

const root = postcss.parse('a { background: white }')
root.nodes[0].append({ prop: 'color', value: 'black' })
root.nodes[0].nodes[1].raws.before   //=> undefined
root.nodes[0].nodes[1].raw('before') //=> ' '

Returns string. Code style value.

Node#remove()

Removes the node from its parent and cleans the parent properties from the node and its children.

if (decl.prop.match(/^-webkit-/)) {
  decl.remove()
}

Returns default. Node to make calls chain.

Node#replaceWith()

Inserts node(s) before the current node and removes the current node.

AtRule: {
  mixin: atrule => {
    atrule.replaceWith(mixinRules[atrule.params])
  }
}

Returns default. Current node to methods chain.

Node#root()

Finds the Root instance of the node’s tree.

root.nodes[0].nodes[0].root() === root

Returns default. Root parent.

Node#toJSON()

Fix circular links on JSON.stringify().

Returns object. Cleaned object.

Node#toString()

Returns a CSS string representing the node.

new Rule({ selector: 'a' }).toString() //=> "a {}"

Returns string. CSS string of this node.

Node#warn()

This method is provided as a convenience wrapper for Result#warn.

  Declaration: {
    bad: (decl, { result }) => {
      decl.warn(result, 'Deprecated property bad')
    }
  }

Returns default. Created warning object.

PreviousMap

Source map information from input CSS. For example, source map after Sass compiler.

This class will automatically find source map in input CSS or in file system near input file (according from option).

const root = parse(css, { from: 'a.sass.css' })
root.input.map //=> PreviousMap

PreviousMap#annotation

sourceMappingURL content.

Type: string.

PreviousMap#file

The CSS source identifier. Contains Input#file if the user set the from option, or Input#id if they did not.

Type: string.

PreviousMap#inline

Was source map inlined by data-uri to input CSS.

Type: boolean.

PreviousMap#mapFile

Path to source map file.

Type: string.

PreviousMap#root

The directory with source map file, if source map is in separated file.

Type: string.

PreviousMap#text

Source map file content.

Type: string.

PreviousMap#consumer()

Create a instance of SourceMapGenerator class from the source-map library to work with source map information.

It is lazy method, so it will create object only on first call and then it will use cache.

Returns SourceMapConsumer. Object with source map information.

PreviousMap#withContent()

Does source map contains sourcesContent with input source text.

Returns boolean. Is sourcesContent present.

Processor

Contains plugins to process CSS. Create one Processor instance, initialize its plugins, and then use that instance on numerous CSS files.

const processor = postcss([autoprefixer, postcssNested])
processor.process(css1).then(result => console.log(result.css))
processor.process(css2).then(result => console.log(result.css))

Processor#plugins

Plugins added to this processor.

const processor = postcss([autoprefixer, postcssNested])
processor.plugins.length //=> 2

Type: (Plugin | Transformer | TransformCallback)[].

Processor#version

Current PostCSS version.

if (result.processor.version.split('.')[0] !== '6') {
  throw new Error('This plugin works only with PostCSS 6')
}

Type: string.

Processor#process()

Parses source CSS and returns a LazyResult Promise proxy. Because some plugins can be asynchronous it doesn’t make any transformations. Transformations will be applied in the LazyResult methods.

processor.process(css, { from: 'a.css', to: 'a.out.css' })
  .then(result => {
     console.log(result.css)
  })

Returns default | default. Promise proxy.

Processor#use()

Adds a plugin to be used as a CSS processor.

PostCSS plugin can be in 4 formats:

• A plugin in Plugin format.
• A plugin creator function with pluginCreator.postcss = true. PostCSS will call this function without argument to get plugin.
• A function. PostCSS will pass the function a @{link Root} as the first argument and current Result instance as the second.
• Another Processor instance. PostCSS will copy plugins from that instance into this one.

Plugins can also be added by passing them as arguments when creating a postcss instance (see [postcss(plugins)]).

Asynchronous plugins should return a Promise instance.

const processor = postcss()
  .use(autoprefixer)
  .use(postcssNested)

Returns default. Current processor to make methods chain.

Result

Provides the result of the PostCSS transformations.

A Result instance is returned by LazyResult#then or Root#toResult methods.

postcss([autoprefixer]).process(css).then(result => {
 console.log(result.css)
})

const result2 = postcss.parse(css).toResult()

Result#css

A CSS string representing of Result#root.

postcss.parse('a{}').toResult().css //=> "a{}"

Type: string.

Result#lastPlugin

Last runned PostCSS plugin.

Type: Plugin | TransformCallback.

Result#map

An instance of SourceMapGenerator class from the source-map library, representing changes to the Result#root instance.

result.map.toJSON() //=> { version: 3, file: 'a.css', … }

if (result.map) {
  fs.writeFileSync(result.opts.to + '.map', result.map.toString())
}

Type: SourceMap.

Result#messages

Contains messages from plugins (e.g., warnings or custom messages). Each message should have type and plugin properties.

AtRule: {
  import: (atRule, { result }) {
    const importedFile = parseImport(atRule)
    result.messages.push({
      type: 'dependency',
      plugin: 'postcss-import',
      file: importedFile,
      parent: result.opts.from
    })
  }
}

Type: Message[].

Result#opts

Options from the Processor#process or Root#toResult call that produced this Result instance.]

root.toResult(opts).opts === opts

Type: ResultOptions.

Result#processor

The Processor instance used for this transformation.

for (const plugin of result.processor.plugins) {
  if (plugin.postcssPlugin === 'postcss-bad') {
    throw 'postcss-good is incompatible with postcss-bad'
  }
})

Type: default.

Result#root

Root node after all transformations.

root.toResult().root === root

Type: default | default.

Result#content

An alias for the Result#css property. Use it with syntaxes that generate non-CSS output.

result.css === result.content

Result#toString()

Returns for Result#css content.

result + '' === result.css

Returns string. String representing of Result#root.

Result#warn()

Creates an instance of Warning and adds it to Result#messages.

if (decl.important) {
  result.warn('Avoid !important', { node: decl, word: '!important' })
}

Returns default. Created warning.

Result#warnings()

Returns warnings from plugins. Filters Warning instances from Result#messages.

result.warnings().forEach(warn => {
  console.warn(warn.toString())
})

Returns default[]. Warnings from plugins.

Root

Represents a CSS file and contains all its parsed nodes.

const root = postcss.parse('a{color:black} b{z-index:2}')
root.type         //=> 'root'
root.nodes.length //=> 2

Root#nodes

An array containing the container’s children.

const root = postcss.parse('a { color: black }')
root.nodes.length           //=> 1
root.nodes[0].selector      //=> 'a'
root.nodes[0].nodes[0].prop //=> 'color'

Type: ChildNode[].

Root#parent

The node’s parent node.

root.nodes[0].parent === root

Type: default.

Root#raws

Information to generate byte-to-byte equal node string as it was in the origin input.

Every parser saves its own properties, but the default CSS parser uses:

• before: the space symbols before the node. It also stores * and _ symbols before the declaration (IE hack).
• after: the space symbols after the last child of the node to the end of the node.
• between: the symbols between the property and value for declarations, selector and { for rules, or last parameter and { for at-rules.
• semicolon: contains true if the last child has an (optional) semicolon.
• afterName: the space between the at-rule name and its parameters.
• left: the space symbols between /* and the comment’s text.
• right: the space symbols between the comment’s text and */.
• important: the content of the important statement, if it is not just !important.

PostCSS cleans selectors, declaration values and at-rule parameters from comments and extra spaces, but it stores origin content in raws properties. As such, if you don’t change a declaration’s value, PostCSS will use the raw value with comments.

const root = postcss.parse('a {\n  color:black\n}')
root.first.first.raws //=> { before: '\n  ', between: ':' }

Type: RootRaws.

Root#source

The input source of the node.

The property is used in source map generation.

If you create a node manually (e.g., with postcss.decl()), that node will not have a source property and will be absent from the source map. For this reason, the plugin developer should consider cloning nodes to create new ones (in which case the new node’s source will reference the original, cloned node) or setting the source property manually.

decl.source.input.from //=> '/home/ai/a.sass'
decl.source.start      //=> { line: 10, column: 2 }
decl.source.end        //=> { line: 10, column: 12 }

// Bad
const prefixed = postcss.decl({
  prop: '-moz-' + decl.prop,
  value: decl.value
})

// Good
const prefixed = decl.clone({ prop: '-moz-' + decl.prop })

if (atrule.name === 'add-link') {
  const rule = postcss.rule({ selector: 'a', source: atrule.source })
  atrule.parent.insertBefore(atrule, rule)
}

Type: Source.

Root#type

tring representing the node’s type. Possible values are root, atrule, rule, decl, or comment.

new Declaration({ prop: 'color', value: 'black' }).type //=> 'decl'

Type: "root".

Root#first

The container’s first child.

rule.first === rules.nodes[0]

Root#last

The container’s last child.

rule.last === rule.nodes[rule.nodes.length - 1]

Root#after()

Insert new node after current node to current node’s parent.

Just alias for node.parent.insertAfter(node, add).

decl.after('color: black')

Returns default. This node for methods chain.

Root#append()

Inserts new nodes to the end of the container.

const decl1 = new Declaration({ prop: 'color', value: 'black' })
const decl2 = new Declaration({ prop: 'background-color', value: 'white' })
rule.append(decl1, decl2)

root.append({ name: 'charset', params: '"UTF-8"' })  // at-rule
root.append({ selector: 'a' })                       // rule
rule.append({ prop: 'color', value: 'black' })       // declaration
rule.append({ text: 'Comment' })                     // comment

root.append('a {}')
root.first.append('color: black; z-index: 1')

Returns default. This node for methods chain.

Root#assign()

Assigns properties to the current node.

decl.assign({ prop: 'word-wrap', value: 'break-word' })

Returns default. Current node to methods chain.

Root#before()

Insert new node before current node to current node’s parent.

Just alias for node.parent.insertBefore(node, add).

decl.before('content: ""')

Returns default. This node for methods chain.

Root#cleanRaws()

Clear the code style properties for the node and its children.

node.raws.before  //=> ' '
node.cleanRaws()
node.raws.before  //=> undefined

Root#clone()

Returns an exact clone of the node.

The resulting cloned node and its (cloned) children will retain code style properties.

decl.raws.before    //=> "\n  "
const cloned = decl.clone({ prop: '-moz-' + decl.prop })
cloned.raws.before  //=> "\n  "
cloned.toString()   //=> -moz-transform: scale(0)

Returns default. Clone of the node.

Root#cloneAfter()

Shortcut to clone the node and insert the resulting cloned node after the current node.

Returns default. New node.

Root#cloneBefore()

Shortcut to clone the node and insert the resulting cloned node before the current node.

decl.cloneBefore({ prop: '-moz-' + decl.prop })

Returns default. New node

Root#each()

Iterates through the container’s immediate children, calling callback for each child.

Returning false in the callback will break iteration.

This method only iterates through the container’s immediate children. If you need to recursively iterate through all the container’s descendant nodes, use Container#walk.

Unlike the for {}-cycle or Array#forEach this iterator is safe if you are mutating the array of child nodes during iteration. PostCSS will adjust the current index to match the mutations.

const root = postcss.parse('a { color: black; z-index: 1 }')
const rule = root.first

for (const decl of rule.nodes) {
  decl.cloneBefore({ prop: '-webkit-' + decl.prop })
  // Cycle will be infinite, because cloneBefore moves the current node
  // to the next index
}

rule.each(decl => {
  decl.cloneBefore({ prop: '-webkit-' + decl.prop })
  // Will be executed only for color and z-index
})

Returns void | false. Returns false if iteration was broke.

Root#error()

Returns a CssSyntaxError instance containing the original position of the node in the source, showing line and column numbers and also a small excerpt to facilitate debugging.

If present, an input source map will be used to get the original position of the source, even from a previous compilation step (e.g., from Sass compilation).

This method produces very useful error messages.

if (!variables[name]) {
  throw decl.error(`Unknown variable ${name}`, { word: name })
  // CssSyntaxError: postcss-vars:a.sass:4:3: Unknown variable $black
  //   color: $black
  // a
  //          ^
  //   background: white
}

Returns default. Error object to throw it.

Root#every()

Returns true if callback returns true for all of the container’s children.

const noPrefixes = rule.every(i => i.prop[0] !== '-')

Returns boolean. Is every child pass condition.

Root#index()

Returns a child’s index within the Container#nodes array.

rule.index( rule.nodes[2] ) //=> 2

Returns number. Child index.

Root#insertAfter()

Insert new node after old node within the container.

Returns default. This node for methods chain.

Root#insertBefore()

Insert new node before old node within the container.

rule.insertBefore(decl, decl.clone({ prop: '-webkit-' + decl.prop }))

Returns default. This node for methods chain.

Root#next()

Returns the next child of the node’s parent. Returns undefined if the current node is the last child.

if (comment.text === 'delete next') {
  const next = comment.next()
  if (next) {
    next.remove()
  }
}

Returns ChildNode. Next node.

Root#positionBy()

Get the position for a word or an index inside the node.

Returns Position. Position.

Root#positionInside()

Convert string index to line/column.

Returns Position. Symbol position in file.

Root#prepend()

Inserts new nodes to the start of the container.

const decl1 = new Declaration({ prop: 'color', value: 'black' })
const decl2 = new Declaration({ prop: 'background-color', value: 'white' })
rule.prepend(decl1, decl2)

root.append({ name: 'charset', params: '"UTF-8"' })  // at-rule
root.append({ selector: 'a' })                       // rule
rule.append({ prop: 'color', value: 'black' })       // declaration
rule.append({ text: 'Comment' })                     // comment

root.append('a {}')
root.first.append('color: black; z-index: 1')

Returns default. This node for methods chain.

Root#prev()

Returns the previous child of the node’s parent. Returns undefined if the current node is the first child.

const annotation = decl.prev()
if (annotation.type === 'comment') {
  readAnnotation(annotation.text)
}

Returns ChildNode. Previous node.

Root#push()

Add child to the end of the node.

rule.push(new Declaration({ prop: 'color', value: 'black' }))

Returns default. This node for methods chain.

Root#rangeBy()

Get the range for a word or start and end index inside the node. The start index is inclusive; the end index is exclusive.

Returns Range. Range.

Root#raw()

Returns a Node#raws value. If the node is missing the code style property (because the node was manually built or cloned), PostCSS will try to autodetect the code style property by looking at other nodes in the tree.

const root = postcss.parse('a { background: white }')
root.nodes[0].append({ prop: 'color', value: 'black' })
root.nodes[0].nodes[1].raws.before   //=> undefined
root.nodes[0].nodes[1].raw('before') //=> ' '

Returns string. Code style value.

Root#remove()

Removes the node from its parent and cleans the parent properties from the node and its children.

if (decl.prop.match(/^-webkit-/)) {
  decl.remove()
}

Returns default. Node to make calls chain.

Root#removeAll()

Removes all children from the container and cleans their parent properties.

rule.removeAll()
rule.nodes.length //=> 0

Returns default. This node for methods chain.

Root#removeChild()

Removes node from the container and cleans the parent properties from the node and its children.

rule.nodes.length  //=> 5
rule.removeChild(decl)
rule.nodes.length  //=> 4
decl.parent        //=> undefined