Angular HttpPromise: difference between `success`/`error` methods and `then`'s arguments
angularjs, promise
Solution
NB This answer is factually incorrect; as pointed out by a comment below, success() does return the original promise. I'll not change; and leave it to OP to edit.
The major difference between the 2 is that `.then()` call returns a promise (resolved with a value returned from a callback) while `.success()` is more traditional way of registering callbacks and doesn't return a promise.
Promise-based callbacks (`.then()`) make it easy to chain promises (do a call, interpret results and then do another call, interpret results, do yet another call etc.).
The `.success()` method is a streamlined, convenience method when you don't need to chain call nor work with the promise API (for example, in routing).
In short:
- `.then()` - full power of the promise API but slightly more verbose
- `.success()` - doesn't return a promise but offeres slightly more convienient syntax
Problem
According to AngularJS doc, calls to `$http` return the following: Returns a promise object with the standard then method and two http specific methods: success and error. The then method takes two arguments a success and an error callback which will be called with a response object. The success and error methods take a single argument - a function that will be called when the request succeeds or fails respectively. The arguments passed into these functions are destructured representation of the response object passed into the then method. Aside from the fact that the `response` object is destructured in one case, I don't get the difference between - the success/error callbacks passed to be passed as arguments of `promise.then` - the callbacks passed as arguments for the `promise.success`/`promise.error` methods of the promise Is there any? What's the point of these two different ways to pass seemingly identical callbacks?