when document load do something js code example
Example 1: JavaScript that executes after page load
//two ways of executing JS code after page is loaded, use "DOMContentLoaded" when able
document.addEventListener("DOMContentLoaded", function(){
//dom is fully loaded, but maybe waiting on images & css files
});
window.addEventListener("load", function(){
//everything is fully loaded, don't use me if you can use DOMContentLoaded
});
Example 2: html tag run only after whole page is loaded
<body onload="script();">
<!-- will call the function script when the body is load -->