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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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