Why does the javascript code inside the "JS" window display an error ? Is it possible to work in this window ?

Question

Code :
var text = document.createTextNode("Hello World");
            var div  = document.getElementById("text");
            div.appendChild(text);

 The error refers to the line with the following code:

div.appendChild(text);

 Error : Uncaught TypeError : Cannot read property 'appendChild' of null

The code only works in the "HTML" window as below
       <script type="text/javascript">
            var text = document.createTextNode("Hello World");
            var div  = document.getElementById("text");
            div.appendChild(text);
        </script

Answer 1

You should do:

window.onload = function () {
// JS code here
}

The error is because JS is loaded before DOM ( HTML )