event trigger when document loads javascript code example

Example 1: how to trigger events when the document loads in js

document.addEventListener("DOMContentLoaded", ready);
function ready() {
    alert('DOM is ready');

    // image is not yet loaded (unless it was cached), so the size is 0x0
    alert(`Image size: ${img.offsetWidth}x${img.offsetHeight}`);
}

Example 2: js document onload

//use
window.onload=()=>{};