Document: readyState property

switch (document.readyState) {   case "loading":     // The document is loading.     break;   case "interactive": {     // The document has finished loading and we can access DOM elements.     // Sub-resources such as scripts, images, stylesheets and frames are still loading.     const span = document.createElement("span");     span.textContent = "A <span> element.";     document.body.appendChild(span);     break;   }   case "complete":     // The page is fully loaded.     console.log(       `The first CSS rule is: ${document.styleSheets[0].cssRules[0].cssText}`,     );     break; } 

// Alternative to DOMContentLoaded event document.onreadystatechange = () => {   if (document.readyState === "interactive") {     initApplication();   } }; 

// Alternative to load event document.onreadystatechange = () => {   if (document.readyState === "complete") {     initApplication();   } }; 

document.addEventListener("readystatechange", (event) => {   if (event.target.readyState === "interactive") {     initLoader();   } else if (event.target.readyState === "complete") {     initApp();   } });