JAVASCRIPT

call javascript function after page load complete

//for jquery
//after document load
$(document).ready(function() {   //same as: $(function() { 
     alert("hi 1");
});
//after full window load including image src css file
$(window).load(function() {
     alert("hi 2");
});

html load script after page load

<script defer src="app.js"></script>

call javascript function after page load complete

document.addEventListener('readystatechange', event => { 

    // When HTML/DOM elements are ready:
    if (event.target.readyState === "interactive") {   //does same as:  ..addEventListener("DOMContentLoaded"..
        alert("hi 1");
    }

    // When window loaded ( external resources are loaded too- `css`,`src`, etc...) 
    if (event.target.readyState === "complete") {
        alert("hi 2");
    }
});