is-whatwg-url

Is this value a WHATWG-standard URL object?

Example

const assert = require('assert');
const isURL = require('is-whatwg-url');

const url = new URL('about:blank');

assert.equal(isURL(url), true);
assert.equal(isURL(Object.assign({ constructor: URL, __proto__: URL.prototype }, url)), false);

native engine version support matrix

Engine	✅ toString and/or getters brand check	⚠️ non-standard URLContext Symbol property (no brand check)	⚠️ no methods (no brand check)	❌ non-constructor URL	❌ no URL
chrome	>= 32		23 - 31		<= 22
safari	>= 6.2				<= 6.1
firefox	>= 26			4 - 25	<= 3.6
node	>= 20	6 - 20			< 6

Caveats:

• firefox 26 - 28: toString does not brand check, but accessors do
• chrome 32-44, firefox 26+, node 20.0 - 20.11: the error message is bad/unclear/inaccurate, but a TypeError is correctly thrown
• node from v6 - 20, inclusive, does not properly brand check, but instead looks for a URLContext object appearing behind a public non-global symbol (Object.getOwnPropertySymbols(new URL('about:blank'))[0]). As such, this library uses the most rigorous heuristics possible to determine if something is a URL.
  • node v6 - v18.16, inclusive, also looks for public non-global symbol (Object.getOwnPropertySymbols(new URL('about:blank'))[1]). property that is the same value as .searchParams on the URL instance
• prior to node v10.0, URL was not a global, but is accessible with require('url').URL

Tests

Simply clone the repo, npm install, and run npm test