WeakSet.prototype.has()

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

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
hasChrome Full support 36Edge Full support 12Firefox Full support 34IE No support NoOpera Full support 23Safari Full support 9WebView Android Full support 37Chrome Android Full support 36Firefox Android Full support 34Opera Android Full support 24Safari iOS Full support 9Samsung Internet Android Full support 3.0nodejs Full support 0.12

Legend

Full support  
Full support
No support  
No support

See also

Related Topics
  1. Standard built-in objects
  2. WeakSet
  3. Methods
    1. WeakSet.prototype.add()
    2. WeakSet.prototype.clear()
    3. WeakSet.prototype.delete()
    4. WeakSet.prototype.has()
  4. Inheritance:
  5. Function
  6. Properties
    1. Function.arguments
    2. Function.arity
    3. Function.caller
    4. Function.displayName
    5. Function.length
    6. Function.name
  7. Methods
    1. Function.prototype.apply()
    2. Function.prototype.bind()
    3. Function.prototype.call()
    4. Function.prototype.isGenerator()
    5. Function.prototype.toSource()
    6. Function.prototype.toString()
  8. Object
  9. Properties
    1. Object.prototype.__count__
    2. Object.prototype.__noSuchMethod__
    3. Object.prototype.__parent__
    4. Object.prototype.__proto__
    5. Object.prototype.constructor
  10. Methods
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.unwatch()
    12. Object.prototype.valueOf()
    13. Object.prototype.watch()
    14. Object.setPrototypeOf()