WeakSet.prototype.has() - JavaScript 编辑

The has() method returns a boolean indicating whether an object exists in a WeakSet or not.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

ws.has(value);

Parameters

value

Required. The object to test for presence in the WeakSet.

Return value

Boolean

Returns true if an element with the specified value exists in the WeakSet object; otherwise false.

Examples

Using the has method

var ws = new WeakSet();
var obj = {};
ws.add(window);

mySet.has(window);  // returns true
mySet.has(obj);     // returns false

Specifications

Specification
ECMAScript (ECMA-262) The definition of 'WeakSet.prototype.has' in that specification.

Browser compatibility

BCD tables only load in the browser

See also

• WeakSet
• WeakSet.prototype.add()
• WeakSet.prototype.delete()