✨ add interval() helper to consume a stream of intervals

[cowboyd]

Motivation

setInterval() is a core JavaScript API that allows you to setup global state. As such, there really isn't any reason that you shouldn't consume it using structured concurrency.

Approach

This adds an interval() function that constructs a stream that emits an item every time that the interval is triggered.

let startTime = Date.now();

for (let _ of yield* each(interval(10))) {
  let elapsed = Date.now() - startTime;
  console.log(`elapsed time: ${elapsed} ms`);
  yield* each.next();
}

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/thefrontside/effection@1005

commit: 1bbc61d

[taras]

Do you know if this change remains compatible with https://docs.deno.com/examples/mocking_tutorial/#faking-time?

[cowboyd]

@taras It definitely should because the interval helper is just another caller to setInterval() in the same way that sleep() is just a client of setTimeout(). It doesn't patch in any way.

We could actually use it to write a test to find out! .... but we'd have to make sure that it was compatible with nodejs

[taras]

🤦 I'm sorry, I read this in passing. I didn't notice that this is a contrib update - it doesn't change the underlying sleep command.

[taras]

👍

[jbolda]

Seems great with me!