They are not part of the specification nor is there a standard way of accessing them that you could use to get the internal state of the promise to construct a polyfill. However, you can convert any standard promise into one that has these values by creating a wrapper,
function MakeQuerablePromise(promise) {
// Don't create a wrapper for promises that can already be queried.
if (promise.isResolved) return promise;
var isResolved = false;
var isRejected = false;
// Observe the promise, saving the fulfillment in a closure scope.
var result = promise.then(
function(v) { isResolved = true; return v; },
function(e) { isRejected = true; throw e; });
result.isFulfilled = function() { return isResolved || isRejected; };
result.isResolved = function() { return isResolved; }
result.isRejected = function() { return isRejected; }
return result;
}
This doesn't affect all promises, as modifying the prototype would, but it does allow you to convert a promise into a promise that exposes it state.
