feat: improve Promise-compliance

[jonaskuske]

FYI, got both the subclassed version and the standalone one (doesn't rely on Promise at all) to work!
Both pass your tests and the A+ test suite and I managed to get the types working, too :)

You can switch between the implementations by adjusting the commented exports at the bottom in DeferredPromise.ts, and run the tests with npm test && npm run test-aplus.

Give them a try and feel free to use them or to borrow stuff for your impl :)

[kettanaito]

This is truly impressive! Thank you so much for working on this.

I like the subclass implementation since we can rely on the native Promise that way. It'd be great if we could reuse/change the createDeferredExecutor function so it can be used standalone and also power the subclass. I will see if I can do that.

[kettanaito]

I rewrote it a bit to use a deferred executor. The tests are passing, I think it works as expected.

[kettanaito]

This looks fantastic! Thank you, @jonaskuske!

Is there any way I can buy you a coffee?

[jonaskuske]

Thanks! Glad the integration with the external executor fn went so smoothly :)
(and thanks for the readme mention!)

As for ☕, there's ko-fi or paypal.me, if you want 😊