Promise_addScript.js

  function addScript(attribute, text) {
    return new Promise(function(resolve, reject) {

        var script = document.createElement('script');
        for (var attr in attribute) {
            var value = attribute[attr];
            if (value) {
              script.setAttribute(attr, value);
            }
        }
        script.innerHTML = text;

        script.onload = resolve;
        script.onerror = reject;

        document.body.appendChild(script);
    });
  }