Last Updated : 23 Jul, 2025
The Set.add() method in JavaScript is used to append an element with a specified value in a set. It modifies the existing set by appending the new element but does not return a new set. The Set.add() method does not modify the set if the element with a specified value already exists in the set.
Syntax:mySet.add(value);Parameters:
Example 1: In this example, we have added two numbers 23 and 12 into the set.
JavaScript
// Create a new set using Set() constructor
let myset = new Set();
// Append new elements to the
// set using add() method
myset.add(23);
myset.add(12);
// Print the modified set
console.log(myset);
Example 2: Adding elements using add() with chaining and checking if duplicate values exist or not.
JavaScript
// Create a new set using Set() constructor
let myset = new Set();
// Append new elements to the set
// using add() method with chaining
myset.add(23).add(12);
// Appending an already existing
// element to the set this
// element will not be added to the set
// as it contains only distinct elements
myset.add(23);
// Print the modified set
console.log(myset);
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