페이지 리소스 로드 후 실행(execute function after complete page load)

document.addEventListener('readystatechange', function () {
    if (event.target.readyState === "interactive") {
        // same as:  document.addEventListener("DOMContentLoaded"...
        // same as  jQuery.ready
        console.log("All HTML DOM elements are accessible");
    }

    if (event.target.readyState === "complete") {
        console.log("Now external resources are loaded too, like css,src etc... ");
    }
});