JavaScript Array unshift() Method
The 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: This method accepts a single parameter.
- 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.
Below is an example of the Array unshift() method.
Example 1:
JavaScript
<script> function func() { // Original array var array = ["GFG", "Geeks", "for", "Geeks"]; // Checking for condition in array var value = array.unshift("GeeksforGeeks"); console.log(value); console.log(array); } func();</script> |
Output:
5 GeeksforGeeks,GFG,Geeks,for,Geeks
Example 2: In this example, the function unshift() adds 28 and 65 to the front of the array.
JavaScript
<script> function sayHello() { var arr = [23,76,19,94]; // Adding elements to the front of the array console.log(arr.unshift(28,65)); console.log(arr); } sayHello();</script> |
Output:
6 28,65,23,76,19,94
Example 3: In this example, the shift() method tries to remove the first element of the array, but the array is empty, therefore it returns undefined.
JavaScript
<script> function sayHello() { var arr = [23,76,19,94]; console.log(arr.shift()); } sayHello();</script> |
Output:
undefined
We have a complete list of Javascript Array methods, to check those please go through this Javascript Array Complete reference article.
Supported Browsers: The browsers supported by the JavaScript Array unshift() method are listed below:
- Google Chrome 1 and above
- Edge 12 and above
- Firefox 1 and above
- Internet Explorer 5.5 and above
- Opera 4 and above
- Safari 1 and above
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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