Css-selector-parser NPM

css-selector-parser

Fast and low memory CSS selector parser.
Parses CSS selector into object-model (AST).
Compliant with all historical and modern CSS specs.
Covered with tests.
Documented.
Supported CSS selector standards:
- css1: https://www.w3.org/TR/CSS1/
- css2: https://www.w3.org/TR/CSS2/
- css3/selectors-3: https://www.w3.org/TR/selectors-3/
- selectors-4: https://www.w3.org/TR/selectors-4/
- latest: refers to selectors-4
- progressive: latest + accepts unknown psudo-classes, psudo-elements and attribute case sensitivity modifiers

Important:

Latest releases: Changelog.

Installation

npm install css-selector-parser

Usage

Parsing

import {createParser} from 'css-selector-parser';

const parse = createParser();
const selector = parse('a[href^="/"], .container:has(nav) > a[href]:nth-child(2)::before');

console.log(selector);

Produces:

({
    type: 'Selector',
    rules: [
        {
            type: 'Rule',
            items: [
                { type: 'TagName', name: 'a' },
                {
                    type: 'Attribute',
                    name: 'href',
                    operator: '^=',
                    value: { type: 'String', value: '/' }
                }
            ]
        },
        {
            type: 'Rule',
            items: [
                { type: 'ClassName', name: 'container' },
                {
                    type: 'PseudoClass',
                    name: 'has',
                    argument: {
                        type: 'Selector',
                        rules: [
                            {
                                type: 'Rule',
                                items: [ { type: 'TagName', name: 'nav' } ]
                            }
                        ]
                    }
                }
            ],
            nestedRule: {
                type: 'Rule',
                items: [
                    { type: 'TagName', name: 'a' },
                    { type: 'Attribute', name: 'href' },
                    {
                        type: 'PseudoClass',
                        name: 'nth-child',
                        argument: { type: 'Formula', a: 0, b: 2 }
                    },
                    {
                        type: 'PseudoElement',
                        name: 'before'
                    }
                ],
                combinator: '>'
            }
        }
    ]
})

Constructing AST and rendering

import {ast, render} from 'css-selector-parser';

const selector = ast.selector({
    rules: [
        ast.rule({
            items: [
                ast.tagName({name: 'a'}),
                ast.attribute({name: 'href', operator: '^=', value: ast.string({value: '/'})})
            ]
        }),
        ast.rule({
            items: [
                ast.className({name: 'container'}),
                ast.pseudoClass({
                    name: 'has',
                    argument: ast.selector({
                        rules: [ast.rule({items: [ast.tagName({name: 'nav'})]})]
                    })
                })
            ],
            nestedRule: ast.rule({
                combinator: '>',
                items: [
                    ast.tagName({name: 'a'}),
                    ast.attribute({name: 'href'}),
                    ast.pseudoClass({
                        name: 'nth-child',
                        argument: ast.formula({a: 0, b: 2})
                    }),
                    ast.pseudoElement({name: 'before'})
                ]
            })
        })
    ]
});

console.log(render(selector)); // a[href^="/"], .container:has(nav) > a[href]:nth-child(2)::before