Mastering the JavaScript Set Function: Examples & Concepts

Introduction to JavaScript Set Function

The JavaScript Set function is a powerful and efficient data structure that allows you to store unique values of any data type, whether it's primitive or an object reference. Sets can be valuable when you want to eliminate duplicate values from an array or work with unique values in general. In this article, we'll dive into the fundamentals of JavaScript Set, explore its methods, and learn how to use it effectively with clear examples.

Creating and Initializing a JavaScript Set

To create a new Set, you simply use the 'new' keyword, followed by the 'Set()' constructor. You can also initialize your Set with an iterable object, such as an array, as an argument:

const mySet = new Set([1, 2, 3]);

This creates a new Set containing the unique values 1, 2, and 3. Note that if the given iterable contains duplicate values, the Set will automatically remove them:

const arrayWithDuplicates = [1, 1, 2, 2, 3, 3];
const uniqueSet = new Set(arrayWithDuplicates);

Fundamental JavaScript Set Methods

Now that you know how to create a Set, let's explore some of the most common methods you'll use to interact with this data structure:

1. set.add(value): To add a value to a Set, use the 'add()' method. Keep in mind that this method will only add unique values, ignoring duplicates:

mySet.add(4); // This duplicate value will be ignored

2. set.has(value): To check if a Set contains a specific value, use the 'has()' method:

mySet.has(1); // true
mySet.has(5); // false

3. set.delete(value): To remove a value from a Set, use the 'delete()' method:


4. set.clear(): To remove all values from a Set, use the 'clear()' method:


5. set.size: To get the number of elements in a Set, use the 'size' property:

mySet.size; // 3

JavaScript Set Iteration

JavaScript Sets can be iterated using the 'for...of' loop or the 'forEach()' method. Here are examples for both methods:

// Using for...of loop
for (const value of mySet) {

// Using forEach()
mySet.forEach(value => {

In conclusion, the JavaScript Set function is a powerful, versatile data structure for managing unique values. By understanding and effectively using Sets, you can improve the readability and performance of your code.