jquery loaded

by mtenschert

HTML

<!DOCTYPE HTML> 
<html> 
  
<head> 
    <title> 
        JavaScript  
      | Check if jquery has been loaded, If not then load. 
    </title> 

</head> 
  
<body style="text-align:center;" 
      id="body"> 
    <h1 style="color:green;">   
            GeeksForGeeks   
        </h1> 
    <p id="GFG_UP" 
       style="font-size: 19px;  
              font-weight: bold;"> 
    </p> 
    <button onClick="GFG_Fun()"> 
        click here 
    </button> 
    <p id="GFG_DOWN" 
       style="color: green;  
              font-size: 24px;  
              font-weight: bold;"> 
    </p> 
    <script> 
        var up = document.getElementById('GFG_UP'); 
        var down = document.getElementById('GFG_DOWN'); 
        up.innerHTML = "Click on button to check whether JQuery is loaded"; 
  
        function () { 
            if (!window.jQuery) { 
                var el = document.createElement('script'); 
                el.type = "text/javascript"; 
                el.src = "https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js"; 
                document.getElementsByTagName('head')[0].appendChild(el); 
                down.innerHTML = "Script loaded succesfully!"; 
            } else { 
                down.innerHTML = "Script already loaded!"; 
            } 
        } 
    </script> 
</body> 
  
</html>

JavaScript

if (!window.jQuery) { 
                var el = document.createElement('script'); 
                el.type = "text/javascript"; 
                el.src = "https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js"; 
                document.getElementsByTagName('head')[0].appendChild(el); 
                down.innerHTML = "Script loaded succesfully!";
                
                
            } else { 
                
            }