Promises vs Observables example

to demonstrate the difference between promises and observables I'll create this promise that returns a value of dog after 100 milliseconds and then I'll execute this promise by calling that then and simply logging the result into console and here we see our dog now using the same approach let's create an observable where I will copy this existing settimeout function and replace this resolved with observer dot next and again I'll execute this observable by calling dot subscribe and put the value into console and here it is now to demonstrate the first main difference between observables and promises I'm going to duplicate this dot next goal and along with dog returned cat and bird and we see it in the console now let me try to do the same thing in the existing promise and it just doesn't work you can't do that with promises so the first difference is that observables can return multiple values another cool thing about observables is that they behave like arrays so here I can call dot filter and filter out any other values that are not a bird and here we get just the bird in the console and one more thing with observables I can save a reference to the subscription just like that and then call unsubscribe to cancel it which cancels the observable you can't do that with promises

Channel: Irek Mirgaleev

Views: 24,174

Rating: 4.9836736 out of 5

Keywords: promise, observable, javascript

Id: 3rbikUwGf9Y

Length: 1min 56sec (116 seconds)

Published: Thu Oct 10 2019

Reddit Comments

[u/beardedheathen]

Just in general for me I dislike YouTube tutorials vs just a webpage with text and picture examples. I don't know about other people but I figure out might be worth mentioning to little looking to get more views