JavaScript weakSet add() Method

Last Updated : 11 Jul, 2025

Javascript weakSet.add() is used to add an object at the end of the object WeakSet. The WeakSet object lets you store weakly held objects in a collection.

Syntax:

weakSet.add(A);

Parameters: This method accepts a single parameter value.

  • value: This value will be added to the weakset object. 

Return Values: It returns the newly added weakset object.

Below are examples of weakSet.add() method:

Example 1: This is a basic example of weakset.add() method in javascript.

javascript 
function gfg() {
    const weakset = new WeakSet();

    const object1 = {};
    weakset.add(object1);
    console.log(weakset.has(object1));
}
gfg();

Output
true

Example 2: Here the output is true because the newly created objects have been set to the end of the weakSet() object.

javascript 
// Constructing a weakset object
const weakset = new WeakSet();

// Constructing a new object object1
const object1 = {};
const object2 = {};
const object3 = {};
const object4 = {};

// Adding the object1 at the end of the weakset object.
weakset.add(object1);
weakset.add(object2);
weakset.add(object3);
weakset.add(object4);

// Printing either object has been added or not
console.log(weakset.has(object1));
console.log(weakset.has(object2));
console.log(weakset.has(object3));
console.log(weakset.has(object4));

Output
true
true
true
true

Example 3: Here the output is false because the newly created objects have not been set to the end of the weakSet() object.

javascript 
// Constructing a weakset object
const weakset = new WeakSet();

// Constructing a new object object1
const object1 = {};
const object2 = {};
const object3 = {};
const object4 = {};

// Printing either object has been added or not
console.log(weakset.has(object1));
console.log(weakset.has(object2));
console.log(weakset.has(object3));
console.log(weakset.has(object4));

Output
false
false
false
false

Supported Browsers:

  • Google Chrome 36 and above
  • Firefox 34 and above
  • Apple Safari 9 and above
  • Opera 23 and above
  • Edge 12 and above

We have a complete list of Javascript WeakSet methods, to check those please go through Javascript WeakSet Complete reference article.

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