Promise vs Observable for Http in Angular2? [duplicate]

Question

Essentially, what the title says, is there any reason to use an observable over a promise for the purposes of making http calls? Seems like needless overcomplication, since all the call will do is succeed or fail, and there is no real reason to cancel it, virtually ever. Asking this for the typical use-case, not for the typical observables sales-pitch of debounce (which, ironically, ng-debounce does just fine anyway, without making useless calls).

Answer 1

There is a huge advantage of observables that is quite relevant here.

Observable supports cancellation while Promise doesn't.

Using subscribe() and map(), instead of then() doesn't seem to add much complication to me. You can also use toPromise() to get a Promise if that is what you need.

See also Angular - Promise vs Observable for more details.

Also if FRP style of programming is used it's handy to get an observable everywhere. If that is not desired just using toPromise() gives a Promise and the slightly simpler API.

Answer 2

The very basic difference between promise and observable is Observable module will not work if no functionality subscribed to it. Hence less burden to your server.

Where as in promise, whether you are truly utilising the response or not, it will send you a promise object after pinging your server with your request and payload; Which sometime undesirable.

The funda is to decrease the load of node or other server.