ES6 script loader

scriptloader.js

import qs from 'qs';
/*

 loadScript('https://example.com/script.js').then(() => {
   // do something
 }).catch(e => console.log(e));
 
 const loadjQuery = async () => {
   try {
      await loadscript('https://code.jquery.com/jquery-3.2.1.js');
     // use jquery code
   } catch (e) {
      console.log(e);
   }
 } 
*/
export const loadScript = (url, params) => new Promise((res, rej) => {
  const script = document.createElement('script');
  let realUrl = url;

  script.onload = res;
  script.onerror = rej;

  if (typeof params !== 'undefined') {
    realUrl += qs.stringify(params);
  }

  if (document.querySelectorAll(`[src="${realUrl}"]`).length === 0) {
    script.src = realUrl;
    document.body.appendChild(script);
  } else {
    res();
  }
});