PV247
Vilém Jeniš
Asynchronous
operations
Vilém Jeniš
JAVASCRIPT:
I'm a:
- single threaded
- concurrent language
I have
- a call stack
- an event loop
- a callback queue
- and some other APIs and stuff.
JAVASCRIPT:
I'm a:
- single threaded
- concurrent language
I have
- a call stack
- an event loop
- a callback queue
- and some other APIs and stuff.
JAVASCRIPT:
I'm a:
- single threaded
- concurrent language
I have
- a call stack
- an event loop
- a callback queue
- and some other APIs and stuff.
JAVASCRIPT:
I'm a:
- single threaded
- concurrent language
I have
- a call stack
- an event loop
- a callback queue
- and some other APIs and stuff.
Here‘s another one…
JAVASCRIPT:
I'm a:
- single threaded
- concurrent language
I have
- a call stack
- an event loop
- a callback queue
- and some other APIs and stuff.
Event loop
Previous slides borrowed from: https://www.youtube.com/watch?v=8aGhZQkoFbQ
More here: http://latentflip.com/loupe/
Question time! (Remind me if I forget…)
Callback hell
What is a Promise?
A promise is an object that may produce a single value
some time in the future: either a resolved value, or a reason
that it’s not resolved (e.g., a network error occurred). A
promise may be in one of 3 possible states: fulfilled,
rejected, or pending. Promise users can attach callbacks to
handle the fulfilled value or the reason for rejection.
Promises are eager, meaning that a promise will start doing
whatever task you give it as soon as the promise
constructor is invoked.
Promises as a Railway
What if nothing can go wrong?
How to stop an error I‘ve dealt with?
Source: https://fsharpforfunandprofit.com/rop/ <- Seriously… Look at the presentation at least once!
It‘s all the same.