|
|
- # API Documentation
-
- *Please use only this documented API when working with the parser. Methods
- not documented here are subject to change at any point.*
-
- ## `parser` function
-
- This is the module's main entry point.
-
- ```js
- const parser = require('postcss-selector-parser');
- ```
-
- ### `parser([transform], [options])`
-
- Creates a new `processor` instance
-
- ```js
- const processor = parser();
- ```
-
- Or, with optional transform function
-
- ```js
- const transform = selectors => {
- selectors.walkUniversals(selector => {
- selector.remove();
- });
- };
-
- const processor = parser(transform)
-
- // Example
- const result = processor.processSync('*.class');
- // => .class
- ```
-
- [See processor documentation](#processor)
-
- Arguments:
-
- * `transform (function)`: Provide a function to work with the parsed AST.
- * `options (object)`: Provide default options for all calls on the returned `Processor`.
-
- ### `parser.attribute([props])`
-
- Creates a new attribute selector.
-
- ```js
- parser.attribute({attribute: 'href'});
- // => [href]
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.className([props])`
-
- Creates a new class selector.
-
- ```js
- parser.className({value: 'button'});
- // => .button
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.combinator([props])`
-
- Creates a new selector combinator.
-
- ```js
- parser.combinator({value: '+'});
- // => +
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- Notes:
- * **Descendant Combinators** The value of descendant combinators created by the
- parser always just a single space (`" "`). For descendant selectors with no
- comments, additional space is now stored in `node.spaces.before`. Depending
- on the location of comments, additional spaces may be stored in
- `node.raws.spaces.before`, `node.raws.spaces.after`, or `node.raws.value`.
- * **Named Combinators** Although, nonstandard and unlikely to ever become a standard,
- named combinators like `/deep/` and `/for/` are parsed as combinators. The
- `node.value` is name after being unescaped and normalized as lowercase. The
- original value for the combinator name is stored in `node.raws.value`.
-
-
- ### `parser.comment([props])`
-
- Creates a new comment.
-
- ```js
- parser.comment({value: '/* Affirmative, Dave. I read you. */'});
- // => /* Affirmative, Dave. I read you. */
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.id([props])`
-
- Creates a new id selector.
-
- ```js
- parser.id({value: 'search'});
- // => #search
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.nesting([props])`
-
- Creates a new nesting selector.
-
- ```js
- parser.nesting();
- // => &
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.pseudo([props])`
-
- Creates a new pseudo selector.
-
- ```js
- parser.pseudo({value: '::before'});
- // => ::before
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.root([props])`
-
- Creates a new root node.
-
- ```js
- parser.root();
- // => (empty)
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.selector([props])`
-
- Creates a new selector node.
-
- ```js
- parser.selector();
- // => (empty)
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.string([props])`
-
- Creates a new string node.
-
- ```js
- parser.string();
- // => (empty)
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.tag([props])`
-
- Creates a new tag selector.
-
- ```js
- parser.tag({value: 'button'});
- // => button
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ### `parser.universal([props])`
-
- Creates a new universal selector.
-
- ```js
- parser.universal();
- // => *
- ```
-
- Arguments:
-
- * `props (object)`: The new node's properties.
-
- ## Node types
-
- ### `node.type`
-
- A string representation of the selector type. It can be one of the following;
- `attribute`, `class`, `combinator`, `comment`, `id`, `nesting`, `pseudo`,
- `root`, `selector`, `string`, `tag`, or `universal`. Note that for convenience,
- these constants are exposed on the main `parser` as uppercased keys. So for
- example you can get `id` by querying `parser.ID`.
-
- ```js
- parser.attribute({attribute: 'href'}).type;
- // => 'attribute'
- ```
-
- ### `node.parent`
-
- Returns the parent node.
-
- ```js
- root.nodes[0].parent === root;
- ```
-
- ### `node.toString()`, `String(node)`, or `'' + node`
-
- Returns a string representation of the node.
-
- ```js
- const id = parser.id({value: 'search'});
- console.log(String(id));
- // => #search
- ```
-
- ### `node.next()` & `node.prev()`
-
- Returns the next/previous child of the parent node.
-
- ```js
- const next = id.next();
- if (next && next.type !== 'combinator') {
- throw new Error('Qualified IDs are not allowed!');
- }
- ```
-
- ### `node.replaceWith(node)`
-
- Replace a node with another.
-
- ```js
- const attr = selectors.first.first;
- const className = parser.className({value: 'test'});
- attr.replaceWith(className);
- ```
-
- Arguments:
-
- * `node`: The node to substitute the original with.
-
- ### `node.remove()`
-
- Removes the node from its parent node.
-
- ```js
- if (node.type === 'id') {
- node.remove();
- }
- ```
-
- ### `node.clone()`
-
- Returns a copy of a node, detached from any parent containers that the
- original might have had.
-
- ```js
- const cloned = parser.id({value: 'search'});
- String(cloned);
-
- // => #search
- ```
-
- ### `node.isAtPosition(line, column)`
-
- Return a `boolean` indicating whether this node includes the character at the
- position of the given line and column. Returns `undefined` if the nodes lack
- sufficient source metadata to determine the position.
-
- Arguments:
-
- * `line`: 1-index based line number relative to the start of the selector.
- * `column`: 1-index based column number relative to the start of the selector.
-
- ### `node.spaces`
-
- Extra whitespaces around the node will be moved into `node.spaces.before` and
- `node.spaces.after`. So for example, these spaces will be moved as they have
- no semantic meaning:
-
- ```css
- h1 , h2 {}
- ```
-
- For descendent selectors, the value is always a single space.
-
- ```css
- h1 h2 {}
- ```
-
- Additional whitespace is found in either the `node.spaces.before` and `node.spaces.after` depending on the presence of comments or other whitespace characters. If the actual whitespace does not start or end with a single space, the node's raw value is set to the actual space(s) found in the source.
-
- ### `node.source`
-
- An object describing the node's start/end, line/column source position.
-
- Within the following CSS, the `.bar` class node ...
-
- ```css
- .foo,
- .bar {}
- ```
-
- ... will contain the following `source` object.
-
- ```js
- source: {
- start: {
- line: 2,
- column: 3
- },
- end: {
- line: 2,
- column: 6
- }
- }
- ```
-
- ### `node.sourceIndex`
-
- The zero-based index of the node within the original source string.
-
- Within the following CSS, the `.baz` class node will have a `sourceIndex` of `12`.
-
- ```css
- .foo, .bar, .baz {}
- ```
-
- ## Container types
-
- The `root`, `selector`, and `pseudo` nodes have some helper methods for working
- with their children.
-
- ### `container.nodes`
-
- An array of the container's children.
-
- ```js
- // Input: h1 h2
- selectors.at(0).nodes.length // => 3
- selectors.at(0).nodes[0].value // => 'h1'
- selectors.at(0).nodes[1].value // => ' '
- ```
-
- ### `container.first` & `container.last`
-
- The first/last child of the container.
-
- ```js
- selector.first === selector.nodes[0];
- selector.last === selector.nodes[selector.nodes.length - 1];
- ```
-
- ### `container.at(index)`
-
- Returns the node at position `index`.
-
- ```js
- selector.at(0) === selector.first;
- selector.at(0) === selector.nodes[0];
- ```
-
- Arguments:
-
- * `index`: The index of the node to return.
-
- ### `container.atPosition(line, column)`
-
- Returns the node at the source position `index`.
-
- ```js
- selector.at(0) === selector.first;
- selector.at(0) === selector.nodes[0];
- ```
-
- Arguments:
-
- * `index`: The index of the node to return.
-
- ### `container.index(node)`
-
- Return the index of the node within its container.
-
- ```js
- selector.index(selector.nodes[2]) // => 2
- ```
-
- Arguments:
-
- * `node`: A node within the current container.
-
- ### `container.length`
-
- Proxy to the length of the container's nodes.
-
- ```js
- container.length === container.nodes.length
- ```
-
- ### `container` Array iterators
-
- The container class provides proxies to certain Array methods; these are:
-
- * `container.map === container.nodes.map`
- * `container.reduce === container.nodes.reduce`
- * `container.every === container.nodes.every`
- * `container.some === container.nodes.some`
- * `container.filter === container.nodes.filter`
- * `container.sort === container.nodes.sort`
-
- Note that these methods only work on a container's immediate children; recursive
- iteration is provided by `container.walk`.
-
- ### `container.each(callback)`
-
- Iterate the container's immediate children, calling `callback` for each child.
- You may return `false` within the callback to break the iteration.
-
- ```js
- let className;
- selectors.each((selector, index) => {
- if (selector.type === 'class') {
- className = selector.value;
- return false;
- }
- });
- ```
-
- Note that unlike `Array#forEach()`, this iterator is safe to use whilst adding
- or removing nodes from the container.
-
- Arguments:
-
- * `callback (function)`: A function to call for each node, which receives `node`
- and `index` arguments.
-
- ### `container.walk(callback)`
-
- Like `container#each`, but will also iterate child nodes as long as they are
- `container` types.
-
- ```js
- selectors.walk((selector, index) => {
- // all nodes
- });
- ```
-
- Arguments:
-
- * `callback (function)`: A function to call for each node, which receives `node`
- and `index` arguments.
-
- This iterator is safe to use whilst mutating `container.nodes`,
- like `container#each`.
-
- ### `container.walk` proxies
-
- The container class provides proxy methods for iterating over types of nodes,
- so that it is easier to write modules that target specific selectors. Those
- methods are:
-
- * `container.walkAttributes`
- * `container.walkClasses`
- * `container.walkCombinators`
- * `container.walkComments`
- * `container.walkIds`
- * `container.walkNesting`
- * `container.walkPseudos`
- * `container.walkTags`
- * `container.walkUniversals`
-
- ### `container.split(callback)`
-
- This method allows you to split a group of nodes by returning `true` from
- a callback. It returns an array of arrays, where each inner array corresponds
- to the groups that you created via the callback.
-
- ```js
- // (input) => h1 h2>>h3
- const list = selectors.first.split(selector => {
- return selector.type === 'combinator';
- });
-
- // (node values) => [['h1', ' '], ['h2', '>>'], ['h3']]
- ```
-
- Arguments:
-
- * `callback (function)`: A function to call for each node, which receives `node`
- as an argument.
-
- ### `container.prepend(node)` & `container.append(node)`
-
- Add a node to the start/end of the container. Note that doing so will set
- the parent property of the node to this container.
-
- ```js
- const id = parser.id({value: 'search'});
- selector.append(id);
- ```
-
- Arguments:
-
- * `node`: The node to add.
-
- ### `container.insertBefore(old, new)` & `container.insertAfter(old, new)`
-
- Add a node before or after an existing node in a container:
-
- ```js
- selectors.walk(selector => {
- if (selector.type !== 'class') {
- const className = parser.className({value: 'theme-name'});
- selector.parent.insertAfter(selector, className);
- }
- });
- ```
-
- Arguments:
-
- * `old`: The existing node in the container.
- * `new`: The new node to add before/after the existing node.
-
- ### `container.removeChild(node)`
-
- Remove the node from the container. Note that you can also use
- `node.remove()` if you would like to remove just a single node.
-
- ```js
- selector.length // => 2
- selector.remove(id)
- selector.length // => 1;
- id.parent // undefined
- ```
-
- Arguments:
-
- * `node`: The node to remove.
-
- ### `container.removeAll()` or `container.empty()`
-
- Remove all children from the container.
-
- ```js
- selector.removeAll();
- selector.length // => 0
- ```
-
- ## Root nodes
-
- A root node represents a comma separated list of selectors. Indeed, all
- a root's `toString()` method does is join its selector children with a ','.
- Other than this, it has no special functionality and acts like a container.
-
- ### `root.trailingComma`
-
- This will be set to `true` if the input has a trailing comma, in order to
- support parsing of legacy CSS hacks.
-
- ## Selector nodes
-
- A selector node represents a single complex selector. For example, this
- selector string `h1 h2 h3, [href] > p`, is represented as two selector nodes.
- It has no special functionality of its own.
-
- ## Pseudo nodes
-
- A pseudo selector extends a container node; if it has any parameters of its
- own (such as `h1:not(h2, h3)`), they will be its children. Note that the pseudo
- `value` will always contain the colons preceding the pseudo identifier. This
- is so that both `:before` and `::before` are properly represented in the AST.
-
- ## Attribute nodes
-
- ### `attribute.quoted`
-
- Returns `true` if the attribute's value is wrapped in quotation marks, false if it is not.
- Remains `undefined` if there is no attribute value.
-
- ```css
- [href=foo] /* false */
- [href='foo'] /* true */
- [href="foo"] /* true */
- [href] /* undefined */
- ```
-
- ### `attribute.qualifiedAttribute`
-
- Returns the attribute name qualified with the namespace if one is given.
-
- ### `attribute.offsetOf(part)`
-
- Returns the offset of the attribute part specified relative to the
- start of the node of the output string. This is useful in raising
- error messages about a specific part of the attribute, especially
- in combination with `attribute.sourceIndex`.
-
- Returns `-1` if the name is invalid or the value doesn't exist in this
- attribute.
-
- The legal values for `part` are:
-
- * `"ns"` - alias for "namespace"
- * `"namespace"` - the namespace if it exists.
- * `"attribute"` - the attribute name
- * `"attributeNS"` - the start of the attribute or its namespace
- * `"operator"` - the match operator of the attribute
- * `"value"` - The value (string or identifier)
- * `"insensitive"` - the case insensitivity flag
-
- ### `attribute.raws.unquoted`
-
- Returns the unquoted content of the attribute's value.
- Remains `undefined` if there is no attribute value.
-
- ```css
- [href=foo] /* foo */
- [href='foo'] /* foo */
- [href="foo"] /* foo */
- [href] /* undefined */
- ```
-
- ### `attribute.spaces`
-
- Like `node.spaces` with the `before` and `after` values containing the spaces
- around the element, the parts of the attribute can also have spaces before
- and after them. The for each of `attribute`, `operator`, `value` and
- `insensitive` there is corresponding property of the same nam in
- `node.spaces` that has an optional `before` or `after` string containing only
- whitespace.
-
- Note that corresponding values in `attributes.raws.spaces` contain values
- including any comments. If set, these values will override the
- `attribute.spaces` value. Take care to remove them if changing
- `attribute.spaces`.
-
- ### `attribute.raws`
-
- The raws object stores comments and other information necessary to re-render
- the node exactly as it was in the source.
-
- If a comment is embedded within the identifiers for the `namespace`, `attribute`
- or `value` then a property is placed in the raws for that value containing the full source of the propery including comments.
-
- If a comment is embedded within the space between parts of the attribute
- then the raw for that space is set accordingly.
-
- Setting an attribute's property `raws` value to be deleted.
-
- For now, changing the spaces required also updating or removing any of the
- raws values that override them.
-
- Example: `[ /*before*/ href /* after-attr */ = /* after-operator */ te/*inside-value*/st/* wow */ /*omg*/i/*bbq*/ /*whodoesthis*/]` would parse as:
-
- ```js
- {
- attribute: "href",
- operatator: "=",
- value: "test",
- spaces: {
- before: '',
- after: '',
- attribute: { before: ' ', after: ' ' },
- operator: { after: ' ' },
- value: { after: ' ' },
- insensitive: { after: ' ' }
- },
- raws: {
- spaces: {
- attribute: { before: ' /*before*/ ', after: ' /* after-attr */ ' },
- operator: { after: ' /* after-operator */ ' },
- value: { after: '/* wow */ /*omg*/' },
- insensitive: { after: '/*bbq*/ /*whodoesthis*/' }
- },
- unquoted: 'test',
- value: 'te/*inside-value*/st'
- }
- }
- ```
-
- ## `Processor`
-
- ### `ProcessorOptions`
-
- * `lossless` - When `true`, whitespace is preserved. Defaults to `true`.
- * `updateSelector` - When `true`, if any processor methods are passed a postcss
- `Rule` node instead of a string, then that Rule's selector is updated
- with the results of the processing. Defaults to `true`.
-
- ### `process|processSync(selectors, [options])`
-
- Processes the `selectors`, returning a string from the result of processing.
-
- Note: when the `updateSelector` option is set, the rule's selector
- will be updated with the resulting string.
-
- **Example:**
-
- ```js
- const parser = require("postcss-selector-parser");
- const processor = parser();
-
- let result = processor.processSync(' .class');
- console.log(result);
- // => .class
-
- // Asynchronous operation
- let promise = processor.process(' .class').then(result => {
- console.log(result)
- // => .class
- });
-
- // To have the parser normalize whitespace values, utilize the options
- result = processor.processSync(' .class ', {lossless: false});
- console.log(result);
- // => .class
-
- // For better syntax errors, pass a PostCSS Rule node.
- const postcss = require('postcss');
- rule = postcss.rule({selector: ' #foo > a, .class '});
- processor.process(rule, {lossless: false, updateSelector: true}).then(result => {
- console.log(result);
- // => #foo>a,.class
- console.log("rule:", rule.selector);
- // => rule: #foo>a,.class
- })
- ```
-
- Arguments:
-
- * `selectors (string|postcss.Rule)`: Either a selector string or a PostCSS Rule
- node.
- * `[options] (object)`: Process options
-
-
- ### `ast|astSync(selectors, [options])`
-
- Like `process()` and `processSync()` but after
- processing the `selectors` these methods return the `Root` node of the result
- instead of a string.
-
- Note: when the `updateSelector` option is set, the rule's selector
- will be updated with the resulting string.
-
- ### `transform|transformSync(selectors, [options])`
-
- Like `process()` and `processSync()` but after
- processing the `selectors` these methods return the value returned by the
- processor callback.
-
- Note: when the `updateSelector` option is set, the rule's selector
- will be updated with the resulting string.
-
- ### Error Handling Within Selector Processors
-
- The root node passed to the selector processor callback
- has a method `error(message, options)` that returns an
- error object. This method should always be used to raise
- errors relating to the syntax of selectors. The options
- to this method are passed to postcss's error constructor
- ([documentation](http://api.postcss.org/Container.html#error)).
-
- #### Async Error Example
-
- ```js
- let processor = (root) => {
- return new Promise((resolve, reject) => {
- root.walkClasses((classNode) => {
- if (/^(.*)[-_]/.test(classNode.value)) {
- let msg = "classes may not have underscores or dashes in them";
- reject(root.error(msg, {
- index: classNode.sourceIndex + RegExp.$1.length + 1,
- word: classNode.value
- }));
- }
- });
- resolve();
- });
- };
-
- const postcss = require("postcss");
- const parser = require("postcss-selector-parser");
- const selectorProcessor = parser(processor);
- const plugin = postcss.plugin('classValidator', (options) => {
- return (root) => {
- let promises = [];
- root.walkRules(rule => {
- promises.push(selectorProcessor.process(rule));
- });
- return Promise.all(promises);
- };
- });
- postcss(plugin()).process(`
- .foo-bar {
- color: red;
- }
- `.trim(), {from: 'test.css'}).catch((e) => console.error(e.toString()));
-
- // CssSyntaxError: classValidator: ./test.css:1:5: classes may not have underscores or dashes in them
- //
- // > 1 | .foo-bar {
- // | ^
- // 2 | color: red;
- // 3 | }
- ```
-
- #### Synchronous Error Example
-
- ```js
- let processor = (root) => {
- root.walkClasses((classNode) => {
- if (/.*[-_]/.test(classNode.value)) {
- let msg = "classes may not have underscores or dashes in them";
- throw root.error(msg, {
- index: classNode.sourceIndex,
- word: classNode.value
- });
- }
- });
- };
-
- const postcss = require("postcss");
- const parser = require("postcss-selector-parser");
- const selectorProcessor = parser(processor);
- const plugin = postcss.plugin('classValidator', (options) => {
- return (root) => {
- root.walkRules(rule => {
- selectorProcessor.processSync(rule);
- });
- };
- });
- postcss(plugin()).process(`
- .foo-bar {
- color: red;
- }
- `.trim(), {from: 'test.css'}).catch((e) => console.error(e.toString()));
-
- // CssSyntaxError: classValidator: ./test.css:1:5: classes may not have underscores or dashes in them
- //
- // > 1 | .foo-bar {
- // | ^
- // 2 | color: red;
- // 3 | }
- ```
|