Does await await promise-like objects? [duplicate]

Answer 1

await is going to trigger obj.then(), and that's causing that behavior. Because even if obj is not a Promise, is a thenable object.

You have some information about that here.

In your case it works because:

First tick

1. obj is initialized
2. setTimeout() is executed, its callback will be called in the next tick
3. go() is declared
4. go() is executed
5. await is triggered inside go(), which executes obj.then(), assigning the resolving function to obj.func
6. it has not been resolved yet so the tick ends here

Second tick

1. setTimeout() callback is executed, resolving the promise through obj.func() with the value 57

Third tick

1. the control is back to go(), and the result 57 is logged

Answer 2

From that same page:

If the value is not a Promise, it converts the value to a resolved Promise, and waits for it.

The value will thus automatically be converted to a resolved Promise, and then be waited for.