JavaScript - Insert Element in an array

In JavaScript elements can be inserted at the beginning, end, and at any specific index. JS provides several methods to perform the operations.

At the Beginning

This operation inserts an element at the start of the array. The unshift() method is commonly used, which mutates the original array and returns its new length.

let a = [10, 20, 30, 40];
let e = 50;
a.unshift(e);
console.log(a);

[ 50, 10, 20, 30, 40 ]

You can insert an element at the beginning of an array using many other methods. Refer to this article for more methods.

At the End

To add an element to the end of the array, the push() method is widely used. It mutates the array and returns its updated length.

let a = [10, 20, 30, 40];
let e = 50;
a.push(e);
console.log(a);

[ 10, 20, 30, 40, 50 ]

You can insert an element at the end of an array using many other methods. Refer to this article for more methods.

At a Given Position

To insert an element at a specific index, the splice() method can be used. This method allows adding elements at any position in the array while optionally removing existing ones.

let a = [10, 20, 30, 40];
let pos = 2;
let e = 50;
a.splice(pos, 0, e);
console.log(a);

[ 10, 20, 50, 30, 40 ]

You can insert an element at a specific position in an array using many other methods. Refer to this article for more methods.

Multiple Elements

Using the splice() method, you can also insert multiple elements at a specified index.

let a = [10, 20, 30, 40];
let pos = 2;
let e1 = 50, e2 = 60;
a.splice(pos, 0, e1, e2);
console.log(a);

[ 10, 20, 50, 60, 30, 40 ]

You can insert multiple elements into an array using many other methods. Refer to this article for more methods.