JavaScript Set add() Method Last Updated : 23 Jul, 2025 Comments Improve Suggest changes Like Article Like Report 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:value: It is the value of the new element that is about to get appended to our set.Return value:It returns the set object with an added valueExample 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); OutputSet(2) { 23, 12 } 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); OutputSet(2) { 23, 12 } Supported Browsers:Chrome Edge Firefox OperaSafari Comment More info S shinjanpatra Follow Improve Article Tags : JavaScript Web Technologies JavaScript-Methods JavaScript-Set Explore JavaScript BasicsIntroduction to JavaScript4 min readVariables and Datatypes in JavaScript6 min readJavaScript Operators5 min readControl Statements in JavaScript4 min readArray & StringJavaScript Arrays7 min readJavaScript Array Methods7 min readJavaScript Strings5 min readJavaScript String Methods9 min readFunction & ObjectFunctions in JavaScript5 min readJavaScript Function Expression3 min readFunction Overloading in JavaScript4 min readObjects in JavaScript4 min readJavaScript Object Constructors4 min readOOPObject Oriented Programming in JavaScript3 min readClasses and Objects in JavaScript4 min readWhat Are Access Modifiers In JavaScript ?5 min readJavaScript Constructor Method7 min readAsynchronous JavaScriptAsynchronous JavaScript2 min readJavaScript Callbacks4 min readJavaScript Promise4 min readEvent Loop in JavaScript4 min readAsync and Await in JavaScript2 min readException HandlingJavascript Error and Exceptional Handling6 min readJavaScript Errors Throw and Try to Catch2 min readHow to create custom errors in JavaScript ?2 min readJavaScript TypeError - Invalid Array.prototype.sort argument1 min readDOMHTML DOM (Document Object Model)9 min readHow to select DOM Elements in JavaScript ?3 min readJavaScript Custom Events4 min readJavaScript addEventListener() with Examples9 min readAdvanced TopicsClosure in JavaScript4 min readJavaScript Hoisting6 min readScope of Variables in JavaScript3 min readJavaScript Higher Order Functions7 min readDebugging in JavaScript4 min read Like