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WeakMap.prototype.set()

The set() method of WeakMap instances adds a new element with a specified key and value to this WeakMap.

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Syntax

js
set(key, value)

Parameters

key

Must be either an object or a non-registered symbol. The key of the entry to add to the WeakMap object.

value

Any value representing the value of the entry to add to the WeakMap object.

Return value

The WeakMap object.

Exceptions

TypeError

Thrown if key is not an object or a non-registered symbol.

Examples

Using the set() method

js
const wm = new WeakMap();
const obj = {};

// Add new elements to the WeakMap
wm.set(obj, "foo").set(window, "bar"); // chainable

// Update an element in the WeakMap
wm.set(obj, "baz");

// Using a non-registered symbol as key
const sym = Symbol("foo");
wm.set(sym, "baz");
wm.set(Symbol.iterator, "qux");

Specifications

Specification
ECMAScript Language Specification
# sec-weakmap.prototype.set

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android Deno Node.js
set 36 12
6Before Firefox 38, this method threw a TypeError when the key parameter was not an object. This has been fixed in version 38 and later to return false as per the ES2015 standard.
 23 8 36
6Before Firefox 38, this method threw a TypeError when the key parameter was not an object. This has been fixed in version 38 and later to return false as per the ES2015 standard.
 24 8 3.0 37 1.0 0.12.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap/set