mirror of https://github.com/thangisme/notes.git
625 lines
12 KiB
Markdown
625 lines
12 KiB
Markdown
# API Documentation
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*Please use only this documented API when working with the parser. Methods
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not documented here are subject to change at any point.*
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## `parser` function
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This is the module's main entry point.
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```js
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var parser = require('postcss-selector-parser');
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```
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### `parser([transform])`
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Creates a new `processor` instance
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```js
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var processor = parser();
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// or, with optional transform function
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var transform = function (selectors) {
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selectors.eachUniversal(function (selector) {
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selector.remove();
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});
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};
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var processor = parser(transform)
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// Example
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var result = processor.process('*.class').result;
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// => .class
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```
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[See processor documentation](#processor)
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Arguments:
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* `transform (function)`: Provide a function to work with the parsed AST.
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### `parser.attribute([props])`
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Creates a new attribute selector.
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```js
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parser.attribute({attribute: 'href'});
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// => [href]
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.className([props])`
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Creates a new class selector.
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```js
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parser.className({value: 'button'});
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// => .button
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.combinator([props])`
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Creates a new selector combinator.
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```js
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parser.combinator({value: '+'});
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// => +
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.comment([props])`
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Creates a new comment.
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```js
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parser.comment({value: '/* Affirmative, Dave. I read you. */'});
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// => /* Affirmative, Dave. I read you. */
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.id([props])`
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Creates a new id selector.
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```js
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parser.id({value: 'search'});
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// => #search
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.nesting([props])`
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Creates a new nesting selector.
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```js
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parser.nesting();
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// => &
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.pseudo([props])`
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Creates a new pseudo selector.
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```js
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parser.pseudo({value: '::before'});
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// => ::before
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.root([props])`
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Creates a new root node.
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```js
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parser.root();
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// => (empty)
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.selector([props])`
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Creates a new selector node.
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```js
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parser.selector();
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// => (empty)
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.string([props])`
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Creates a new string node.
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```js
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parser.string();
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// => (empty)
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.tag([props])`
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Creates a new tag selector.
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```js
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parser.tag({value: 'button'});
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// => button
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```
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Arguments:
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* `props (object)`: The new node's properties.
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### `parser.universal([props])`
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Creates a new universal selector.
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```js
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parser.universal();
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// => *
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```
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Arguments:
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* `props (object)`: The new node's properties.
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## Node types
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### `node.type`
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A string representation of the selector type. It can be one of the following;
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`attribute`, `class`, `combinator`, `comment`, `id`, `nesting`, `pseudo`,
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`root`, `selector`, `string`, `tag`, or `universal`. Note that for convenience,
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these constants are exposed on the main `parser` as uppercased keys. So for
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example you can get `id` by querying `parser.ID`.
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```js
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parser.attribute({attribute: 'href'}).type;
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// => 'attribute'
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```
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### `node.parent`
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Returns the parent node.
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```js
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root.nodes[0].parent === root;
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```
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### `node.toString()`, `String(node)`, or `'' + node`
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Returns a string representation of the node.
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```js
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var id = parser.id({value: 'search'});
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console.log(String(id));
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// => #search
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```
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### `node.next()` & `node.prev()`
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Returns the next/previous child of the parent node.
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```js
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var next = id.next();
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if (next && next.type !== 'combinator') {
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throw new Error('Qualified IDs are not allowed!');
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}
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```
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### `node.replaceWith(node)`
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Replace a node with another.
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```js
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var attr = selectors.first.first;
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var className = parser.className({value: 'test'});
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attr.replaceWith(className);
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```
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Arguments:
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* `node`: The node to substitute the original with.
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### `node.remove()`
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Removes the node from its parent node.
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```js
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if (node.type === 'id') {
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node.remove();
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}
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```
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### `node.clone()`
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Returns a copy of a node, detached from any parent containers that the
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original might have had.
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```js
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var cloned = parser.id({value: 'search'});
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String(cloned);
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// => #search
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```
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### `node.spaces`
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Extra whitespaces around the node will be moved into `node.spaces.before` and
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`node.spaces.after`. So for example, these spaces will be moved as they have
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no semantic meaning:
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```css
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h1 , h2 {}
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```
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However, *combinating* spaces will form a `combinator` node:
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```css
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h1 h2 {}
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```
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A `combinator` node may only have the `spaces` property set if the combinator
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value is a non-whitespace character, such as `+`, `~` or `>`. Otherwise, the
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combinator value will contain all of the spaces between selectors.
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### `node.source`
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An object describing the node's start/end, line/column source position.
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Within the following CSS, the `.bar` class node ...
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```css
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.foo,
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.bar {}
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```
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... will contain the following `source` object.
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```js
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source: {
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start: {
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line: 2,
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column: 3
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},
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end: {
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line: 2,
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column: 6
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}
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}
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```
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### `node.sourceIndex`
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The zero-based index of the node within the original source string.
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Within the following CSS, the `.baz` class node will have a `sourceIndex` of `12`.
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```css
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.foo, .bar, .baz {}
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```
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## Container types
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The `root`, `selector`, and `pseudo` nodes have some helper methods for working
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with their children.
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### `container.nodes`
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An array of the container's children.
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```js
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// Input: h1 h2
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selectors.at(0).nodes.length // => 3
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selectors.at(0).nodes[0].value // => 'h1'
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selectors.at(0).nodes[1].value // => ' '
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```
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### `container.first` & `container.last`
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The first/last child of the container.
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```js
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selector.first === selector.nodes[0];
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selector.last === selector.nodes[selector.nodes.length - 1];
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```
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### `container.at(index)`
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Returns the node at position `index`.
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```js
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selector.at(0) === selector.first;
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selector.at(0) === selector.nodes[0];
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```
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Arguments:
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* `index`: The index of the node to return.
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### `container.index(node)`
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Return the index of the node within its container.
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```js
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selector.index(selector.nodes[2]) // => 2
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```
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Arguments:
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* `node`: A node within the current container.
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### `container.length`
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Proxy to the length of the container's nodes.
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```js
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container.length === container.nodes.length
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```
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### `container` Array iterators
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The container class provides proxies to certain Array methods; these are:
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* `container.map === container.nodes.map`
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* `container.reduce === container.nodes.reduce`
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* `container.every === container.nodes.every`
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* `container.some === container.nodes.some`
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* `container.filter === container.nodes.filter`
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* `container.sort === container.nodes.sort`
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Note that these methods only work on a container's immediate children; recursive
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iteration is provided by `container.walk`.
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### `container.each(callback)`
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Iterate the container's immediate children, calling `callback` for each child.
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You may return `false` within the callback to break the iteration.
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```js
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var className;
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selectors.each(function (selector, index) {
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if (selector.type === 'class') {
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className = selector.value;
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return false;
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}
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});
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```
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Note that unlike `Array#forEach()`, this iterator is safe to use whilst adding
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or removing nodes from the container.
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Arguments:
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* `callback (function)`: A function to call for each node, which receives `node`
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and `index` arguments.
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### `container.walk(callback)`
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Like `container#each`, but will also iterate child nodes as long as they are
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`container` types.
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```js
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selectors.walk(function (selector, index) {
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// all nodes
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});
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```
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Arguments:
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* `callback (function)`: A function to call for each node, which receives `node`
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and `index` arguments.
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This iterator is safe to use whilst mutating `container.nodes`,
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like `container#each`.
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### `container.walk` proxies
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The container class provides proxy methods for iterating over types of nodes,
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so that it is easier to write modules that target specific selectors. Those
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methods are:
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* `container.walkAttributes`
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* `container.walkClasses`
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* `container.walkCombinators`
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* `container.walkComments`
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* `container.walkIds`
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* `container.walkNesting`
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* `container.walkPseudos`
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* `container.walkTags`
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* `container.walkUniversals`
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### `container.split(callback)`
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This method allows you to split a group of nodes by returning `true` from
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a callback. It returns an array of arrays, where each inner array corresponds
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to the groups that you created via the callback.
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```js
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// (input) => h1 h2>>h3
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var list = selectors.first.split((selector) => {
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return selector.type === 'combinator';
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});
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// (node values) => [['h1', ' '], ['h2', '>>'], ['h3']]
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```
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Arguments:
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* `callback (function)`: A function to call for each node, which receives `node`
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as an argument.
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### `container.prepend(node)` & `container.append(node)`
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Add a node to the start/end of the container. Note that doing so will set
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the parent property of the node to this container.
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```js
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var id = parser.id({value: 'search'});
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selector.append(id);
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```
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Arguments:
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* `node`: The node to add.
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### `container.insertBefore(old, new)` & `container.insertAfter(old, new)`
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Add a node before or after an existing node in a container:
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```js
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selectors.walk(function (selector) {
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if (selector.type !== 'class') {
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var className = parser.className({value: 'theme-name'});
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selector.parent.insertAfter(selector, className);
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}
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});
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```
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Arguments:
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* `old`: The existing node in the container.
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* `new`: The new node to add before/after the existing node.
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### `container.removeChild(node)`
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Remove the node from the container. Note that you can also use
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`node.remove()` if you would like to remove just a single node.
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```js
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selector.length // => 2
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selector.remove(id)
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selector.length // => 1;
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id.parent // undefined
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```
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Arguments:
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* `node`: The node to remove.
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### `container.removeAll()` or `container.empty()`
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Remove all children from the container.
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```js
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selector.removeAll();
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selector.length // => 0
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```
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## Root nodes
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A root node represents a comma separated list of selectors. Indeed, all
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a root's `toString()` method does is join its selector children with a ','.
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Other than this, it has no special functionality and acts like a container.
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### `root.trailingComma`
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This will be set to `true` if the input has a trailing comma, in order to
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support parsing of legacy CSS hacks.
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## Selector nodes
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A selector node represents a single compound selector. For example, this
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selector string `h1 h2 h3, [href] > p`, is represented as two selector nodes.
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It has no special functionality of its own.
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## Pseudo nodes
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A pseudo selector extends a container node; if it has any parameters of its
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own (such as `h1:not(h2, h3)`), they will be its children. Note that the pseudo
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`value` will always contain the colons preceding the pseudo identifier. This
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is so that both `:before` and `::before` are properly represented in the AST.
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## Attribute nodes
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### `attribute.quoted`
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Returns `true` if the attribute's value is wrapped in quotation marks, false if it is not.
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Remains `undefined` if there is no attribute value.
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```css
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[href=foo] /* false */
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[href='foo'] /* true */
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[href="foo"] /* true */
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[href] /* undefined */
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```
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### `attribute.raws.unquoted`
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Returns the unquoted content of the attribute's value.
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Remains `undefined` if there is no attribute value.
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```css
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[href=foo] /* foo */
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[href='foo'] /* foo */
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[href="foo"] /* foo */
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[href] /* undefined */
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```
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### `attribute.raws.insensitive`
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If there is an `i` specifying case insensitivity, returns that `i` along with the whitespace
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around it.
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```css
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[id=Bar i ] /* " i " */
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[id=Bar i ] /* " i " */
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```
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## `processor`
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### `process(cssText, [options])`
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Processes the `cssText`, returning the parsed output
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```js
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var processor = parser();
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var result = processor.process(' .class').result;
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// => .class
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// To have the parser normalize whitespace values, utilize the options
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var result = processor.process(' .class ', {lossless: false}).result;
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// => .class
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```
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Arguments:
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* `cssText (string)`: The css to be parsed.
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* `[options] (object)`: Process options
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Options:
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* `lossless (boolean)`: false to normalize the selector whitespace, defaults to true
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