Load jQuery library using plain JavaScript (With callback)

dynamically-load-jquery-library-javascript.js

//-  https://www.sitepoint.com/dynamically-load-jquery-library-javascript/
//-  Load jQuery library using plain JavaScript (With callback)           
//-  ---------------------------------------------------------------------

(function () {

    function loadScript(url, callback) {

        var script = document.createElement("script")
        script.type = "text/javascript";

        if (script.readyState) { //IE
            script.onreadystatechange = function () {
                if (script.readyState == "loaded" || script.readyState == "complete") {
                    script.onreadystatechange = null;
                    callback();
                }
            };
        } else { //Others
            script.onload = function () {
                callback();
            };
        }

        script.src = url;
        document.getElementsByTagName("head")[0].appendChild(script);
    }

    loadScript("https://code.jquery.com/jquery-3.4.1.min.js", function () {

         //jQuery loaded
         console.log('jquery loaded');

    });


})();