Are Promise.resolve And New Promise(resolve) Interchangeable

I think Promise.resolve and new Promise(resolve) are interchangeable. Consider this: A. new RSVP.Promise(function (resolve, reject) { resolve(); }).then(function () { retur

Solution 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.

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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.

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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.