fetches a script and returns a promise when it's loaded

GetScript.js

"use strict";
function GetScript(loc) {
    return new Promise((resolve, reject) => {
      fetch(loc)
      .then(res => res.text())
      .then(code => {
        let script = document.createElement('script');
        script.src = URL.createObjectURL(new Blob([code]));
        script.onload = resolve;
        document.head.appendChild(script);
      })
    })
}