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 trueif an element with the specified value exists in theWeakSetobject; otherwisefalse.
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 | Status | Comment | 
|---|---|---|
| ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'WeakSet.prototype.has' in that specification. | Standard | Initial definition. | 
| ECMAScript Latest Draft (ECMA-262) The definition of 'WeakSet.prototype.has' in that specification. | Draft | 
Browser compatibility
| Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari | 
|---|---|---|---|---|---|---|
| Basic support | 36 | (Yes) | 34 (34) | No support | 23 | No support | 
| Feature | Android | Edge | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile | 
|---|---|---|---|---|---|---|
| Basic support | No support | (Yes) | 34.0 (34) | No support | No support | No support |