JavaScript WeakSet

Difficulty Level : Basic
Last Updated : 18 Sep, 2020

Below is the example of weakSet.add() method.

Example:

<script>  
    function gfg() {  
    var weakSetObject = new WeakSet();
    var objectOne = {};
  
    // add(value)
    weakSetObject.add(objectOne);
    document.write("objectOne added </br>");
  
    // has(value)
    document.write("WeakSet has objectTwo : " + 
                    weakSetObject.has(objectTwo));
    }  
    gfg();  
</script>

Output:
```
objectOne added
```

WeakSet in JavaScript is used to store a collection of objects. It adapts the same properties of that of a set i.e. does not store duplicates. The major difference of a WeakSet with the set is that a WeakSet is a collection of objects and not values of some particular type.

Syntax:

new WeakSet(object)

Parameters: Here parameter “object” is an iterable object. All the elements of the iterable object are added to the WeakSet.

Some different WeakSet functions:

METHODS	DESCRIPTION
add(value)	a new object is appended with the given value to the weakset. WeakSet_Object.add(value)
delete(value)	Deletes the value from the WeakSet collection. WeakSet_Object.delete(value)
has(value)	Returns true if the value is present in the WeakSet Collection, false otherwise. WeakSet_Object.has(value)
length()	Returns the length of weakSetObject WeakSet_Object.length()

JavaScript code to show the working of WeakSet() function:

<script>
  
    var weakSetObject = new WeakSet();
    var objectOne = {};
    var objectTwo = {};
  
    // add(value)
    weakSetObject.add(objectOne);
    document.write("objectOne added <br>");
    weakSetObject.add(objectTwo);
    document.write("objectTwo added <br>");
  
    // has(value)
    document.write("WeakSet has objectTwo : " + 
                    weakSetObject.has(objectTwo));
  
    // delete(value)
    weakSetObject.delete(objectTwo);
    document.write("<br>objectTwo deleted<br>");
    document.write("WeakSet has objectTwo : " + 
                    weakSetObject.has(objectTwo));
  
</script>                    

Output:

objectOne added 
objectTwo added 
WeakSet has objectTwo : true
objectTwo deleted
WeakSet has objectTwo : false

Supported Browsers:

Google Chrome
Internet Explorer
Firefox
Apple Safari
Opera

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