javascript - Return Promise result instead of Promise in Nodejs

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Background

I
am trying to learn promises, and I have a promise chain I want to improve
on.

Problem

While
learning how to chain promises, I fail to see why anyone would rather return a promise
instead of returning it's value.

Take the
following example, which uses promise
chaining:

let myObj =
            new MyClass();

myObj.getInfo()
 .then(result =>
            writeOutput(FILE_NAME, result))
 .then(console.log(FILE_NAME + "
            complete"))
 .catch(error =>
            console.error(error));

class
            MyClass{


 getInfo() {
 return new
            Promise(function(fulfil, reject) {
 fulfill("I like bananas");

            });
}

Here I
have to chain 2 times. But if I were to directly return the result from the method
getInfo() instead of returning a Promise I could potentially do
something like the following:

let
            myObj = new MyClass();


let str =
            myObj.getInfo();

writeOutput(FILE_NAME, str)

            .then(console.log(FILE_NAME + " complete"))
 .catch(error =>
            console.error(error));

Questions

So
as you can see I am a little
confused.

1. Given that
   getInfo() is in fact async, is it possible to achieve a similar
   code to the one in my second code sample?


2. If it were
   possible, would it be a good idea? How would you do
   it?

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class="normal">Answer

You can
only return a value from some function if that value is immediately available when that
function is called (on the same tick of the event loop). Remember that
return is
synchronous.

If it is not available right away
then you can only return a promise (or you can use a callback but here you are
specifically asking about
promises).

For a more detailed
explanation see this answer that I wrote some time ago to a question asking on how to
return a result of an AJAX call from some function. I explained why you cannot return
the value but you can return a
promise:

Here is another
related answer - it got downvoted for some reason but I think it explains a similar
issue that you're asking about her: