WeakSet() constructor

The WeakSet() constructor creates {{jsxref("WeakSet")}} objects.

Syntax#

new WeakSet()
new WeakSet(iterable)

[!NOTE] WeakSet() can only be constructed with new. Attempting to call it without new throws a {{jsxref("TypeError")}}.

Parameters#

• iterable {{optional_inline}}
• : If an iterable object is passed, all of its elements will be added to the new WeakSet. null is treated as undefined.

Examples#

Using the WeakSet object#

const ws = new WeakSet();
const foo = {};
const bar = {};

ws.add(foo);
ws.add(bar);

ws.has(foo); // true
ws.has(bar); // true

ws.delete(foo); // removes foo from the set
ws.has(foo); // false, foo has been removed
ws.has(bar); // true, bar is retained

Note that foo !== bar. While they are similar objects, they are not the same object. And so they are both added to the set.

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• Polyfill of WeakSet in core-js
• {{jsxref("WeakSet")}}