is-weakset

Is this value a JS WeakSet? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

Usage no npm install needed!

<script type="module">
  import isWeakset from 'https://cdn.skypack.dev/is-weakset';
</script>

README

is-weakset

Is this value a JS WeakSet? This module works cross-realm/iframe, and despite ES6 @@toStringTag.

Example

var isWeakSet = require('is-weakset');
assert(!isWeakSet(function () {}));
assert(!isWeakSet(null));
assert(!isWeakSet(function* () { yield 42; return Infinity; });
assert(!isWeakSet(Symbol('foo')));
assert(!isWeakSet(1n));
assert(!isWeakSet(Object(1n)));

assert(!isWeakSet(new Set()));
assert(!isWeakSet(new WeakMap()));
assert(!isWeakSet(new Map()));

assert(isWeakSet(new WeakSet()));

class MyWeakSet extends WeakSet {}
assert(isWeakSet(new MyWeakSet()));

Tests

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