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This is a new technology, part of the ECMAScript 2015 (ES6) standard .
This technology's specification has been finalized, but check the compatibility table for usage and implementation status in various browsers.

The delete() method removes the specified element from a WeakMap object.




Required. The key of the element to remove from the WeakMap object.

Return value

Returns true if an element in the WeakMap object has been removed successfully.


Using the delete method

var wm = new WeakMap();
wm.set(window, "foo");

wm.delete(window); // Returns true. Successfully removed.

wm.has(window);    // Returns false. The window object is no longer in the WeakMap.


Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'WeakMap.prototype.delete' in that specification.
Standard Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 36 6.0 (6.0) 11 23 7.1
Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support Not supported 6.0 (6.0) Not supported Not supported 8

Firefox-specific notes

  • Prior to SpiderMonkey 38 (Firefox 38 / Thunderbird 38 / SeaMonkey 2.35), 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 latest ES6 standard (bug 1127827).

See also

Document Tags and Contributors

Contributors to this page: fscholz, realityking
Last updated by: fscholz,