DOM Selector

A CSS selector engine.

Install

npm i @asamuzakjp/dom-selector

Usage

import { DOMSelector } from '@asamuzakjp/dom-selector';
import { JSDOM } from 'jsdom';

const { window } = new JSDOM();
const {
  closest, matches, querySelector, querySelectorAll
} = new DOMSelector(window);

matches(selector, node, opt)

matches - equivalent to Element.matches()

Parameters

• selector string CSS selector
• node object Element node
• opt object? options
  • opt.noexcept boolean? no exception
  • opt.warn boolean? console warn e.g. unsupported pseudo-class

Returns boolean true if matched, false otherwise

closest(selector, node, opt)

closest - equivalent to Element.closest()

Parameters

• selector string CSS selector
• node object Element node
• opt object? options
  • opt.noexcept boolean? no exception
  • opt.warn boolean? console warn e.g. unsupported pseudo-class

Returns object? matched node

querySelector(selector, node, opt)

querySelector - equivalent to Document.querySelector(), DocumentFragment.querySelector() and Element.querySelector()

Parameters

• selector string CSS selector
• node object Document, DocumentFragment or Element node
• opt object? options
  • opt.noexcept boolean? no exception
  • opt.warn boolean? console warn e.g. unsupported pseudo-class

Returns object? matched node

querySelectorAll(selector, node, opt)

querySelectorAll - equivalent to Document.querySelectorAll(), DocumentFragment.querySelectorAll() and Element.querySelectorAll()
NOTE: returns Array, not NodeList

Parameters

• selector string CSS selector
• node object Document, DocumentFragment or Element node
• opt object? options
  • opt.noexcept boolean? no exception
  • opt.warn boolean? console warn e.g. unsupported pseudo-class

Returns Array<(object | undefined)> array of matched nodes

Monkey patch jsdom

import { DOMSelector } from '@asamuzakjp/dom-selector';
import { JSDOM } from 'jsdom';

const dom = new JSDOM('', {
  runScripts: 'dangerously',
  url: 'http://localhost/',
  beforeParse: window => {
    const domSelector = new DOMSelector(window);

    const matches = domSelector.matches.bind(domSelector);
    window.Element.prototype.matches = function (...args) {
      if (!args.length) {
        throw new window.TypeError('1 argument required, but only 0 present.');
      }
      const [selector] = args;
      return matches(selector, this);
    };

    const closest = domSelector.closest.bind(domSelector);
    window.Element.prototype.closest = function (...args) {
      if (!args.length) {
        throw new window.TypeError('1 argument required, but only 0 present.');
      }
      const [selector] = args;
      return closest(selector, this);
    };

    const querySelector = domSelector.querySelector.bind(domSelector);
    window.Document.prototype.querySelector = function (...args) {
      if (!args.length) {
        throw new window.TypeError('1 argument required, but only 0 present.');
      }
      const [selector] = args;
      return querySelector(selector, this);
    };
    window.DocumentFragment.prototype.querySelector = function (...args) {
      if (!args.length) {
        throw new window.TypeError('1 argument required, but only 0 present.');
      }
      const [selector] = args;
      return querySelector(selector, this);
    };
    window.Element.prototype.querySelector = function (...args) {
      if (!args.length) {
        throw new window.TypeError('1 argument required, but only 0 present.');
      }
      const [selector] = args;
      return querySelector(selector, this);
    };

    const querySelectorAll = domSelector.querySelectorAll.bind(domSelector);
    window.Document.prototype.querySelectorAll = function (...args) {
      if (!args.length) {
        throw new window.TypeError('1 argument required, but only 0 present.');
      }
      const [selector] = args;
      return querySelectorAll(selector, this);
    };
    window.DocumentFragment.prototype.querySelectorAll = function (...args) {
      if (!args.length) {
        throw new window.TypeError('1 argument required, but only 0 present.');
      }
      const [selector] = args;
      return querySelectorAll(selector, this);
    };
    window.Element.prototype.querySelectorAll = function (...args) {
      if (!args.length) {
        throw new window.TypeError('1 argument required, but only 0 present.');
      }
      const [selector] = args;
      return querySelectorAll(selector, this);
    };
  }
});

Supported CSS selectors

Pattern	Supported	Note
*	✓
ns|E	✓
*|E	✓
|E	✓
E	✓
E:not(s1, s2, …)	✓
E:is(s1, s2, …)	✓
E:where(s1, s2, …)	✓
E:has(rs1, rs2, …)	✓
E.warning	✓
E#myid	✓
E[foo]	✓
E[foo="bar"]	✓
E[foo="bar" i]	✓
E[foo="bar" s]	✓
E[foo~="bar"]	✓
E[foo^="bar"]	✓
E[foo$="bar"]	✓
E[foo*="bar"]	✓
E[foo|="en"]	✓
E:defined	Partially supported	Matching with MathML is not yet supported.
E:dir(ltr)	✓
E:lang(en)	✓
E:any‑link	✓
E:link	✓
E:visited	✓	Returns false or null to prevent fingerprinting.
E:local‑link	✓
E:target	✓
E:target‑within	✓
E:scope	✓
E:current	Unsupported
E:current(s)	Unsupported
E:past	Unsupported
E:future	Unsupported
E:active	✓
E:hover	✓
E:focus	✓
E:focus‑within	✓
E:focus‑visible	✓
E:open E:closed	Partially supported	Matching with <select>, e.g. select:open, is not supported.
E:enabled E:disabled	✓
E:read‑write E:read‑only	✓
E:placeholder‑shown	✓
E:default	✓
E:checked	✓
E:indeterminate	✓
E:valid E:invalid	✓
E:required E:optional	✓
E:blank	Unsupported
E:user‑valid E:user‑invalid	Unsupported
E:root	✓
E:empty	✓
E:nth‑child(n [of S]?)	✓
E:nth‑last‑child(n [of S]?)	✓
E:first‑child	✓
E:last‑child	✓
E:only‑child	✓
E:nth‑of‑type(n)	✓
E:nth‑last‑of‑type(n)	✓
E:first‑of‑type	✓
E:last‑of‑type	✓
E:only‑of‑type	✓
E F	✓
E > F	✓
E + F	✓
E ~ F	✓
F || E	Unsupported
E:nth‑col(n)	Unsupported
E:nth‑last‑col(n)	Unsupported
E:popover-open	✓
E:state(v)	✓	*1
:host	✓
:host(s)	✓
:host‑context(s)	✓
:host(:state(v))	✓	*1
:host:has(rs1, rs2, ...)	✓
:host(s):has(rs1, rs2, ...)	✓
:host‑context(s):has(rs1, rs2, ...)	✓
&	✓	Only supports outermost &, i.e. equivalent to :scope

*1: ElementInternals.states, i.e. CustomStateSet, is not implemented in jsdom, so you need to apply a patch in the custom element constructor.

class LabeledCheckbox extends window.HTMLElement {
  #internals;
  constructor() {
    super();
    this.#internals = this.attachInternals();
    // patch CustomStateSet
    if (!this.#internals.states) {
      this.#internals.states = new Set();
    }
    this.addEventListener('click', this._onClick.bind(this));
  }
  get checked() {
    return this.#internals.states.has('checked');
  }
  set checked(flag) {
    if (flag) {
      this.#internals.states.add('checked');
    } else {
      this.#internals.states.delete('checked');
    }
  }
  _onClick(event) {
    this.checked = !this.checked;
  }
}

Performance

See benchmark for the latest results.

Acknowledgments

The following resources have been of great help in the development of the DOM Selector.

• CSSTree
• selery
• jsdom
• nwsapi

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Copyright (c) 2023 asamuzaK (Kazz)