The DOM Document Object Model is the hierarchy arrangement of the document which we are working upon.

When the contents and images gets uploaded in the browser this will be the time to load DOM and if that time is over then that portion of the document gets loaded into the web page which we will be opening.

So the event occurred in that case is the PageLoad event and that will render the DOM into the page.

 <script type="text/javascript">
$(document).ready(function(){ 
 // Gets called as soon as DOM is ready
 //code here
 }); 
 </script> 

pageload() method is the initial event that gets loaded when we open our browser. It will render your contents and your images.

So the image whether large or small gets loaded if not fully then partially till that event gets completed.

  <script type="text/javascript">
    function pageLoad() 
     {
     // gets called when page have been fully loaded
     //code here 
    }
     </script>