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 other ways to do this?

What are the limitations? I've read somewhere that jQuery deferred does not support exceptions, so I assume that a promise created out of a deferred would neither. Is this correct?

Answer 1

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

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));