Check that we have done() in func call

Asked Mar 17 '16 at 11:24

Active Mar 20 '16 at 07:02

Viewed 73 times

We have a situation, like on in the following code:

  if (typeof callback === 'undefined') {
    return aggregate;
  }

  return aggregate.exec(callback); // returns promise

If callback not specified - need to return aggregate, and if specified - return promise.

So if we have promise, then we don't have callback and if (typeof callback === 'undefined') would be true, but i need false, because we have promise

The problem is that i can't find any information about how i can know whether .then() existing or not, can someone point me to the right direction?

UPDATE

Explanation:

  if (typeof callback === 'undefined') { // need to check that we don't have .then()
    return aggregate; // need to return this only if we don't have promise AND callback
  }

  return aggregate.exec(callback); // returns promise

UPDATE2

I can't find any information about my situation - i don't think it's duplicate.

The question is - how can we figure out that .then() exists before creating promise?

edited Mar 17 '16 at 12:08

asked Mar 17 '16 at 11:24

alexey

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use this -> if (!(typeof callback === 'undefined')) – blessanm86 Mar 17 '16 at 11:34
i need to return it only in one case: when don't have nor callback, nor promise. – alexey Mar 17 '16 at 11:37
1

Can you put some more relevant code. Its a bit difficult to understand what ur usecase is from your description – blessanm86 Mar 17 '16 at 11:40
see updated answer, i don't know which code could help you understand better – alexey Mar 17 '16 at 11:42
Test for promise like promiseObj.then && typeof promiseObj.then === 'function' – blessanm86 Mar 17 '16 at 11:46
Try not to build double-headed APIs. Just *always* return a promise. Less surprises for everyone, easier to code for you. – Bergi Mar 17 '16 at 11:49
need it for backward compatibilty – alexey Mar 17 '16 at 11:50

Check that we have done() in func call

0 Answers0