August 13, 2026 - A set-like object is an object that provides the following: A size property that contains a number. A has() method that takes an element and returns a boolean.

If an attempt is made to add an element that already exists in the set, the add() method will have no effect, and the set will remain unchanged.

You can now use the JavaScript Set methods to perform set operations like intersection, union and more.

July 13, 2024 - The union() method of Set instances takes a set and returns a new set containing elements which are in either or both of this set and the given set.

February 2, 2024 - By leveraging the Set's built-in methods for adding, checking and removing values, developers can simplify their code and reduce the complexity of handling distinct values. Moreover, the Set object ensures uniqueness, maintains insertion order and provides efficient value existence checks, which makes it a powerful tool in specific use cases. A Map object in JavaScript ...

August 24, 2025 - Sets in JavaScript/TypeScript are a powerful tool for handling collections of unique values. With methods like add(), delete(), has(), and advanced operations like union and intersection, they simplify many common programming tasks.

JavaScript Set Methods · JavaScript Set Logic · JavaScript Weak Sets · JavaScript Set Reference · JavaScript Maps · Set is an ES6 feature. ES6 is fully supported in all modern browsers since June 2017: ❮ Previous Next ❯ · ★ +1 · Sign in to track progress ·

July 10, 2024 - Excellent - finally we can use Set for more than a "duplicate-detector". I only wish that there were some way for objects to be "equal" without them having to be the exact same instance. Kind of like Java's .equals and .hashCode methods ...

const mySet = new Set(); mySet.add("foo"); console.log(mySet.has("foo")); // true console.log(mySet.has("bar")); // false const set = new Set(); const obj = { key1: 1 }; set.add(obj); console.log(set.has(obj)); // true console.log(set.has({ key1: 1 })); // false, because they are different object references console.log(set.add({ key1: 1 })); // now set contains 2 entries

June 27, 2019 - Set is an object that can store any type of JavaScript primitive (think booleans, strings, numbers here), but it will only store unique primitives. Wait... what??? That's awesome! Yeah, my fellow developer, yeah. Instead of using the filter method, all we have to do is pass our postTypes array into the Set object and wrap it into an array.

June 11, 2024 - JavaScript Set Methods A set in JavaScript is a collection of unique values. It means that no value can appear more than once within a set. Sets are often used when you need to store a collection of …

March 6, 2025 - JavaScript developers have been hacking together workarounds for common Set operations like union, intersection, and difference for years. But that’s about to change! With ECMAScript 2024, JavaScript finally introduces native Set methods, making operations on unique value collections faster and easier than ever before.

July 27, 2025 - A Set is a built-in JavaScript object that allows you to store unique values—no duplicates allowed.

January 8, 2021 - <!DOCTYPE html> <script> "use strict";globalThis.__codeBoxId = "p8hj2rbs3i"; let set = new Set(); let john = { name: "John" }; let pete = { name: "Pete" }; let mary = { name: "Mary" }; // visits, some users come multiple times set.add(john); set.add(pete); set.add(mary); set.add(john); set.add(mary); // set keeps only unique values alert( set.size ); // 3 for (let user of set) { alert(user.name); // John (then Pete and Mary) } </script>

September 4, 2024 - */ const mapaches1 = new Set(["Luna", "Apollo", "Orion", Apollo]) /** * Another Set of mapaches' names; the duplicate "Nova" will be removed… ... AI-Native Senior Full-Stack SWE · UI/UX Engineer · TypeScript specialist · 20+ years of SWE · BS & MS age 19 · Doctor of Physical Therapy · DoctorDerek.com ... Pro tutorials about just JavaScript: “vanilla JS” without frameworks, frontend JS, backend JS / Node.js, and the npm package ecosystem.

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const people = ["chris", "chris", "cindy"]; const peopleSet = new Set(people); peopleSet.add("chris"); console.log(peopleSet); // {"chris","cindy"}Code language: JavaScript (javascript) Now they are even more useful with recently universally available methods, as Brian Smith summarizes:

July 23, 2025 - A JavaScript property is a member of an object that associates a key with a value. An instance property is a property that has a new copy for every new instance of the class. Methods are actions that can be performed on objects.