JavaScript Program to Add Element to Start of an Array

In this example, you will learn to write a JavaScript program that adds a new element at the beginning of an array.

To understand this example, you should have the knowledge of the following JavaScript programming topics:


Example 1: Add Element to Array using unshift()

// program to add element to an array

function addElement(arr) {

    // adding new array element
    arr.unshift(4);
    
    console.log(arr);
}

let array = [1, 2, 3];

// calling the function
// passing array argument
addElement(array);

Output

[4, 1, 2, 3]

In the above program, the new element is added to the array variable using the unshift() method.

The unshift() method adds a new element at the beginning of an array.


Example 2: Add Element to Array using splice()

// program to add element to an array

function addElement(arr) {

    // adding element to array
    arr.splice(0, 0, 4);
    
    console.log(arr);
}

let array = [1, 2, 3];

// calling the function
addElement(array);

Output

[4, 1, 2, 3]

In the above program, the splice() method is used to add a new element to an array.

In the splice() method,

  • The first argument is the index of an array where you want to add an element.
  • The second argument is the number of elements that you want to remove from the index element.
  • The third argument is the element that you want to add to the array.

Example 3: Add Element to Array using Spread Operator

// program to add element to an array

function addElement(arr) {

    // adding element to array
    arr = [4, ...arr];
    
    console.log(arr);
}

let array = [1, 2, 3];

// calling the function
addElement(arr);

Output

[4, 1, 2, 3]

In the above program, the spread operator ... is used to add a new element to the beginning of an array.

arr = [4, ...arr]; takes first element as 4 and the rest elements are taken from array.


Example 4: Add Element to Array using concat()

// program to add element to an array

function addElement(arr) {

    // adding element to array
    arr = [4].concat(arr);
    
    console.log(arr);
}

let array = [1, 2, 3];

// calling the function
addElement(array);

Output

[4, 1, 2, 3]

In the above program, the concat() method is used to add a new element to an array.

The concat() method combines two arrays into one.