Are Promise.resolve and new Promise(resolve) interchangeable

Question

I think Promise.resolve and new Promise(resolve) are interchangeable.

Consider this:

A.

new RSVP.Promise(function (         


        

Answer 1

First and foremost

I think Promise.resolve and new Promise(resolve) are interchangeable.

Nope. Promise.resolve will create a promise which is already resolved, whereas new Promise(resolve) creates a promise which is neither resolved nor rejected.

---

In the last example,

return setTimeout(function () {
    return new RSVP.resolve("HI");
}, 3000);

means that, you are returning the result of setTimeout function, not a promise object. So, the current then handler will return a resolved promise with the result of setTimeout. That is why you are seeing a weird object.

---

In your particular case, you want to introduce a delay before resolving the promise. It is not possible with Promise.resolve. The penultimate method you have shown in the question, is the way to go.