Promises?

[espruino-discuss]

Posted at 2018-02-08 by espftw

I saw an old thread referencing Promises, but can't seem to find an official Promise module anywhere. I tried an implementation by @favo from this thread but a simple console.log() test had erroneous results where callbacks occurred before resolutions.

Trying to save a bit of time myself and hoping this was already implemented.

[gfwilliams]

Posted at 2018-02-08 by @gfwilliams

It's built-in to all the new firmwares: http://www.espruino.com/Reference#Promise

I guess you're using ESP8266 so I'm not sure if you're using a build that has it disabled or something, but on an official board with up to date firmware then it's just already there as soon as you type new Promise(...)

[espruino-discuss]

Posted at 2018-05-20 by user90002

I try use promise, but it's work strange:

const p = new Promise(function(resolve, reject) {
  setTimeout(resolve, 100);
  setTimeout(reject, 200);
});

p.then(function() {
    console.log('resolved');
}).catch(function() {
    console.log('rejected');
});

output:

resolved
Uncaught Error: Unhandled promise rejection: undefined

Bolded text printed, because reject called after resolve, but promise must be ignore change state at second call.

And what about async\await?

[gfwilliams]

Posted at 2018-05-21 by @gfwilliams

I try use promise, but it's work strange

This looks like a bug - I've filed one for the issue here: espruino/Espruino#1433

Looks like we didn't test for that as all code I've seen to date just calls one of the other - not both.

And what about async\await?

No, they're not implemented on Espruino.