JavaScript Array unshift() Method

JavaScript Array unshift() Method is used to add one or more elements to the beginning of the given array. This function increases the length of the existing array by the number of elements added to the array.

Syntax:

array.unshift(element1, element2, ..., elementX);

Parameters:

• element: This parameter element is to be added at the beginning of the array.

Return value:

This function returns the new length of the array after inserting the arguments at the beginning of the array. 

Example 1: Below is an example of the Array unshift() method.

function func() {

    // Original array
    let array = ["GFG", "Geeks", "for", "Geeks"];

    // Checking for condition in array
    let value = array.unshift("GeeksforGeeks");
    console.log(value);
    console.log(array);
}
func();

5
[ 'GeeksforGeeks', 'GFG', 'Geeks', 'for', 'Geeks' ]

Example 2: In this example, the function unshift() adds 28 and 65 to the front of the array.

function func() {
    let arr = [23, 76, 19, 94];
    
    // Adding elements to the front of the array
    console.log(arr.unshift(28, 65));
    console.log(arr);
}
func();

6
[ 28, 65, 23, 76, 19, 94 ]

Example 3: In this example, the unshift() method tries to add the element of the array, but the array is empty therefore it adds the value in the empty array.

function func() {
    let arr = [];
    console.log(arr.unshift(1));
}
func();

1

We have a complete list of Javascript Array methods, to check those please go through this Javascript Array Complete reference article.

Supported Browsers:

• Google Chrome 1
• Edge 12
• Firefox 1
• Opera 4
• Safari 1

JavaScript Array unshift() Method – FAQs

What does the Array.prototype.unshift() method do in JavaScript?

The Array.prototype.unshift() method adds one or more elements to the beginning of an array and returns the new length of the array.

Can unshift() be used to add multiple elements at once?

Yes, you can add multiple elements at once by passing them as arguments to unshift(). For example: array.unshift(element1, element2, element3).

How does unshift() affect the indices of existing elements in the array?

The indices of the existing elements in the array are incremented to accommodate the new elements added to the beginning.

Can unshift() handle non-numeric elements?

Yes, unshift() can handle elements of any type, including strings, objects, arrays, and other primitive values.

What are common use cases for the unshift() method?

• Adding Elements to the Beginning: Using unshift() to prepend elements to an array.
• Updating Queue-like Structures: Implementing or modifying data structures like queues where elements need to be added to the front.
• Reversing Order of Operations: Ensuring new elements are processed first by adding them to the beginning of an array.

We have a Cheat Sheet on Javascript where we covered all the important topics of Javascript to check those please go through Javascript Cheat Sheet-A Basic guide to JavaScript.

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