Angular: $ q.defer () vs $ q ()

Question

In Angular, the following snippets seem equivalent:

let deferred = $q.defer();
if(whatever) {
   deferred.resolve('something');
}
else {
   deferred.reject('nah');
}
return deferred.promise;

and

return $q((resolve,reject) => {
    if(whatever) {
       resolve('something');
    }
    else {
       reject('nah');
    }
});

My question is: if they are not equivalent, how do they differ? If they are equivalent, is there a good reason to prefer one over the other?

Answer 1

The second version you posted is the next one, following the Promise / A + -Specification.

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Answer 2

$q promises go, . , , native promises, , (, , , promises ).

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function queryValue(callback) {
  throw new Error("Not implemented yet!!!");
}

function makeConstructorPromise() {
  return new Promise(function(resolve) {
    queryValue(function(value) {
      resolve(value);
    });
  });
}

function makeDeferredPromise() {
  let deferred = Promise.defer();

  queryValue(function(value) {
    deferred.resolve(value);
  });

  return deferred.promise;
}

makeConstructorPromise()
  .catch(function(error) {
    console.error('caught the constructed promise error!', error);
  });

makeDeferredPromise()
  .catch(function(error) {
    // not caught
    console.error('caught the deferred promise error!', error);
  });

<script src="https://cdnjs.cloudflare.com/ajax/libs/bluebird/3.5.1/bluebird.min.js"></script>

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Answer 3

- "".

Kris Kowals Q, promises javascript.

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You can find additional information on this topic and your question directly in Angualar Docu: https://docs.angularjs.org/api/ng/service/ $ q /