Unshift() method to add element at the beginning of an array in JavaScript

unshift(): to add elements to an array

var scripts = new Array();
scripts[0] = "PHP";
scripts[1] = "ASP";
scripts[2] = "JavaScript";
scripts[3] = "HTML";
document.write(scripts.join(" <br> "));
document.write("<br>--Now after applying unshift()--<br>");
scripts.unshift("VBScript","Perl");
document.write(scripts.join(" <br> "));

The above code will add VBScript and Perl at the end of the array and display the full list. Output is here

PHP 
ASP 
JavaScript 
HTML
--Now after applying unshift()--
VBScript 
Perl 
PHP 
ASP 
JavaScript 
HTML

We can add elements at the beginning of an array by using unshift() method. Here is the general syntax for using unshift() method.

scripts.unshift("VBScript","Perl");

We have seen how to add element at the end of an array by using push() method.

Here scripts is our array and we are adding two new elements VBScript and Perl at the beginning of this array by using unshift() method.

unshift with key and value

Array key are re -indexed after using unshift() to add elements.

var scripts = new Array();
scripts[0] = "PHP";
scripts[1] = "ASP";
scripts[2] = "JavaScript";
scripts[3] = "HTML";
scripts.unshift("VBScript","Perl");
for (var key in scripts) {
  document.write("key : " + key + "  =>value: " + scripts[key] + "<br>");
}

Output is here

key : 0 =>value: VBScript
key : 1 =>value: Perl
key : 2 =>value: PHP
key : 3 =>value: ASP
key : 4 =>value: JavaScript
key : 5 =>value: HTML

Adding elements at the end of an array by using push() method Add elements at any position by using splice method
Array Reference How to display elements of an Array

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