Insert at the End of an Array in JavaScript

Here are different ways to add an item at the end of array

1. Using push() Method - Most Used :

The JavaScript Array push() Method is used to add one or more values to the end of the array. This method changes the length of the array by the number of elements added to the array.

const a = [1, 2, 3];
a.push(4);
console.log(a);

// adding multiple element i the last index of array
const b = [10, 20, 30, 40, 50];
b.push(60, 70);
console.log(b);

[ 1, 2, 3, 4 ]
[
  10, 20, 30, 40,
  50, 60, 70
]

2. Using Spread (...) - For adding Multiple Elements

Using the spread (...) operator, you can add elements to the end of an array by creating a new array and combining the original array with the new elements.

let a = [1, 2, 3];
let b = [...a, 4, 5];
console.log(b);

[ 1, 2, 3, 4, 5 ]

3. Using concat() - For adding multiple elements

In this approach, Using the concat() method, create a new array by combining the original array with additional elements. It does not modify the original array, giving a clean way to add elements.

const a = [1, 2, 3];
const b = a.concat(4, 5);
console.log(b);

[ 1, 2, 3, 4, 5 ]

4. Using the length Property - Can add empty spaces

In this approach, we are Using the length property, you can add elements to the end of an array by assigning values to indexes equal to the current length, effectively extending the array with new elements.

let a = [1, 2, 3, 7];
a[a.length] = 4;
a[a.length] = 5;
console.log(a);

[ 1, 2, 3, 7, 4, 5 ]

5. Using splice() Method

Using the splice() method, you can add elements to the end of an array by specifying arr.length as the index and setting the number of elements to remove to 0. It directly modifies the original array.

let a = [1, 2, 3];
a.splice(a.length, 0, 4, 5);
console.log(a);

[ 1, 2, 3, 4, 5 ]

6. Using a loop

Using a loop, you can add multiple elements to the end of an array in JavaScript. Iterate through the elements to be added and assign each to the next available index in the array using its length. This appends the new elements sequentially.

let a = [1, 2, 3];
let b = [4, 5];

for (let i = 0; i < b.length; i++) {
  a[a.length] = b[i];
}

console.log(a); 

[ 1, 2, 3, 4, 5 ]

7. Using apply() Method

The apply() method in JavaScript allows you to call a function with a given this value, and arguments provided as an array. You can use this to add elements to the end of an array by combining the original array with new elements.

let a = [1, 2, 3];
let b = [4, 5];
Array.prototype.push.apply(a, b);
console.log(a);

[ 1, 2, 3, 4, 5 ]

Importance of Adding Elements to an Array

Adding elements to an array is crucial for:

• Building and modifying datasets dynamically.
• Implementing queue and stack operations.
• Enhancing functionality in applications that require data storage and retrieval.