add jquery in js

JavaScript
<!--You can insert Jquery into HTML with the <script> tag in the <head>-->
<!--Insert the next line of code into your <head> tags.-->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script> <!-- jquery (help with javascript) -->/* Adding the script tag to the head as suggested before */

    var head = document.getElementsByTagName('head')[0];
    var script = document.createElement('script');
    script.type = 'text/javascript';
    script.src = "http://code.jquery.com/jquery-2.2.1.min.js";

    // Then bind the event to the callback function.
    // There are several events for cross browser compatibility.
    script.onreadystatechange = handler;
    script.onload = handler;

    // Fire the loading
    head.appendChild(script);

    function handler(){
       console.log('jquery added :)');
    }
Source

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