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Array unshift() method with example in JavaScript

JavaScript unshift() method: Here, we are going to learn about the unshift() method of array in JavaScript.
Submitted by IncludeHelp, on February 28, 2019

JavaScript unshift() method

unshift() method is used to add/insert one or more elements at the beginning of an array. And it returns a new length of the array.

Syntax

array_name.unshift(element1, element2, ...);

Parameters

Elements to be added, one element in required others are optional.

Return value

new length of the array.

Sample Input/Output

Input:
var arr1 = [10, 20, 30, 40, 50];

Function call:
arr1.unshift(111);
arr1.unshift(100,200);
    
Output:
100,200,111,10,20,30,40,50

JavaScript Code to demonstrate example of Array.unshift() method

<html>
<head>
<title>JavaScipt Example</title>
</head>

<body>
	<script>
		var arr1 = [10, 20, 30, 40, 50];
		var arr2 = ["Amit", "Ankur", "Akash"];
		
		//printing arrays before the insering elements
		document.write("arr1: " + arr1 + "<br>");
		document.write("arr1 length: " + arr1.length + "<br>");
		document.write("arr2: " + arr2 + "<br>");
		document.write("arr2 length: " + arr2.length + "<br>");
		
		//adding elements 
		var len1 = arr1.unshift(100,200);
		var len2 = arr2.unshift("Aman");
		
		document.write("<br>After inserting...<br><br>");
		document.write("arr1: " + arr1 + "<br>");
		document.write("new arr1 length: " + len1 + "<br>");
		document.write("arr2: " + arr2 + "<br>");
		document.write("new arr2 length: " + len2 + "<br>");		
		
	</script>
</body>
</html>

Output

arr1: 10,20,30,40,50
arr1 length: 5
arr2: Amit,Ankur,Akash
arr2 length: 3

After inserting...

arr1: 100,200,10,20,30,40,50
new arr1 length: 7
arr2: Aman,Amit,Ankur,Akash
new arr2 length: 4