document.readyState with a Promise()

domReady

/**
 * Module file domReady.js
 */

let domReady = () => {
  return new Promise((resolve, reject) => {
    (document.readyState) || reject("Can't resolve document readystate");
    let listener;
    (/d$|^i|^c/).test(document.readyState) ? resolve() : document.addEventListener("DOMContentLoaded", listener = event => {
      document.removeEventListener("DOMContentLoaded", listener);
      resolve();
    });
  });
}


export { domReady };


/**
 * Main file main.js
 */

import { domReady } from './domready.js';

domReady().then(msg => {
  console.log('DOM has loaded');
}, err => {
  console.log(err);
});