In JavaScript, a new object called Set was introduced in the ES6 version. The Set object is similar to Map, but the major difference is that elements in the Set are unique, and repeated addition of the same type of elements is not possible. A Set can store any type of value, whether primitive or objects. The elements of a Set are iterable and always iterated in the insertion order.

Ordered Elements in a Set

The elements of a Set are ordered, meaning they can be accessed or iterated in the order of their insertion.

Syntax

new Set([iterable]);

Example 1: Basic Set Object Iteration

In this example, we create a basic Set object and iterate over its elements to see the order.

let sample = new Set();
sample.add("Hello");
sample.add("Coders");
sample.add("How");
sample.add("Are");
sample.add("You");
 
let data = sample.values();
for (let val of data) {
    console.log(val);
}

Output

Hello
Coders
How
Are
You

Example 2: Using an Iterator to Access Set Elements

In this example, we use an iterator to access the elements of Set and verify the order of elements.

let sample = new Set();
sample.add("Hello");
sample.add("Coders");
sample.add("How");
sample.add("Are");
sample.add("You");
 
let getit = sample[Symbol.iterator]();
console.log(getit.next());
console.log(getit.next());
console.log(getit.next());
console.log(getit.next());
console.log(getit.next());

Output

{value: 'Hello', done: false}
{value: 'Coders', done: false}
{value: 'How', done: false}
{value: 'Are', done: false}
{value: 'You', done: false}

Explanation

We can easily verify that the elements in the Set follow the same order in which they are inserted.