//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
});

window.addEventListener('load', (event) => {
  console.log('page is fully loaded');
});

window.onload = function() {
  // Some code
};

window.onload = function() {
  // Code here
}