Promise.fulfilled polyfill, to check if a Promise was completed

promise_fulfilled_polyfill.js

Promise = new Proxy(Promise, {
    construct(target, args) {
        let p = new target(...args)
        p.fulfilled = false;
        p.then(()=>p.fulfilled = true)
        p.catch(()=>p.fulfilled = true)
        return p;
      }
  })