How to perform unshift operation without using unshift() method in JavaScript ?
Last Updated :
15 Apr, 2020
The task is to perform unshift operation without using the unshift() method with the help of jQuery. There are two approaches that are discussed below:
Approach 1: We can use the Array concat() method which is used to join two or more arrays. Just pass the newElement as the arrays of size 1 and the rest of the array.
- Example:
<!DOCTYPE HTML>
<html>
<head>
<title>
How to perform the unshift() operation
without using it in JavaScript
</title>
</head>
<body style="text-align:center;">
<h1 style="color:green;">
GeeksforGeeks
</h1>
<p id="GFG_UP">
</p>
<button onclick="myGFG()">
Click Here
</button>
<p id="GFG_DOWN">
</p>
<script>
var array = ['Geeks', 'GFG', 'Geek', 'GeeksforGeeks'];
var up = document.getElementById("GFG_UP");
up.innerHTML = "Array = [" + array + "]";
var down = document.getElementById("GFG_DOWN");
function myGFG() {
var newElement = 'gfg';
newArray = [newElement].concat(array);
down.innerHTML = "Elements of array = ["
+ newArray + "]";
}
</script>
</body>
</html>
|
-
Output:
Approach 2: We can use the ES6 spread operator to perform the operation.
- Example:
<!DOCTYPE HTML>
<html>
<head>
<title>
How to perform the unshift() operation without
using it in JavaScript
</title>
</head>
<body style="text-align:center;">
<h1 style="color:green;">
GeeksforGeeks
</h1>
<p id="GFG_UP">
</p>
<button onclick="myGFG()">
Click Here
</button>
<p id="GFG_DOWN">
</p>
<script>
var array = ['Geeks', 'GFG', 'Geek', 'GeeksforGeeks'];
var up = document.getElementById("GFG_UP");
up.innerHTML = "Array = [" + array + "]";
var down = document.getElementById("GFG_DOWN");
function myGFG() {
var newElement = 'gfg';
newArray = [newElement, ...array];
down.innerHTML = "elements of array = ["
+ newArray + "]";
}
</script>
</body>
</html>
|
-
Output:
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