Suspend

Import from

@gabreusi/hyrax

Runs in

Node, browsers, Deno, Bun

Size budget

Suspend ≤ 700 B

Examples

Run, answers asserted

Suspend notices that the process, tab or machine was suspended: the laptop lid was closed, a browser tab was frozen, a container was paused. It does that by noticing that a timer fired much later than it should have. Use it to reconnect sockets, refresh stale data or resync clocks after a wake-up.

const suspend = new Suspend({ threshold: 5000 });

const off = suspend.on((elapsed) => {
  console.log(`Woke up after ${elapsed} ms`);
  // reconnect your socket, refresh what is stale...
});

off(); // stop listening
suspend.dispose(); // or tear everything down

How it works

• It is an instance, and not a global. Create one where you need it, and dispose() it when you are done.
• The check timer starts with the first listener and stops with the last, so an idle Suspend costs nothing.
• In Node the timer does not keep the process alive.
• threshold (how late counts as a suspension) and interval (how often to check) are options.
• A listener that throws does not stop the others, and { once: true } removes a listener after its first call.

const suspend = new Suspend();
const off = suspend.on((elapsed) => console.log(elapsed), { once: true });
off();
suspend.dispose();

A limit

It reads the wall clock (Date.now()), so changing the system clock by hand can look like a suspension.

Reference

The full signatures, with every option and error, are in the API reference: Suspend, SuspendOptions.