How to convert a jQuery Deferred object to an ES6 Promise

Question

Is this the correct way to convert jQuery Deferred to a Promise?

var p = Promise.resolve($.getJSON(\'api/values\', null));

Are there any ot

Answer 1

I would prefer composition:

const successCb1 = ()=>$.getJSON('api/values'),
successCb2 = (json)=>alert(json),
errorCb = (e)=>alert(e);
Promise
   .resolve()
   .then(successCb1)
   .then(successCb2)
   .catch(errorCb);

Answer 2

I am not sure if that would work. I would recommend:

var p = new Promise(function (resolve, reject) {
  $.getJSON('api/values', null)
    .then(resolve, reject);
});

preferably you could create an adaptorfunction like:

var toPromise = function ($promise) {
  return new Promise(function (resolve, reject) {
    $promise.then(resolve, reject);
  });
});

var p = toPromise($.getJSON('api/values', null));

Answer 3

Yes it should, the Promise.resolve() API supports thenable as argument. So passing a jquery defer object would work just fine.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/resolve#Resolving_thenables_and_throwing_Errors