How to perform unshift operation without using unshift() method in JavaScript ?
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:
Last Updated :
15 Apr, 2020
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