Signals

Utilities to deal with AbortSignal

npm i @hazae41/signals

Node Package 📦

Features

Current features

• 100% TypeScript and ESM
• No external dependencies
• Merge signals
• Optional signals
• Promisify signals

Usage

Never

Signals.never()

This can be useful when you want to accept an optional AbortSignal without branching or doing weird merging

function run(signal: AbortSignal);

// GOOD EXAMPLE
function f(signal = Signals.never()) {
  run(signal)
}

// BAD EXAMPLE
function g(signal?: AbortSignal) {
  if (signal == null)
    run(new AbortController().signal)
  else
    run(signal)
}

Merge

Signals.merge(a, b?)

This can be useful when you have signals with different scopes

const global = AbortSignal.timeout(10 * 1000)

async function f(parent?: AbortSignal) {
  const signal = Signals.merge(global, parent)

  await fetch("...", { signal })
}

resolveOnAbort / rejectOnAbort

Signals.rejectOnAbort(signal)

This is very useful when you want to race a signal with a promise

async function run();

async function runWithTimeout(delay: number) {
  const signal = AbortSignal.timeout(delay)
  using timeout = Signals.rejectOnAbort(signal)

  await Promise.race([run(), timeout.get()])
}

This converts any event-based signal into a disposable promise

You can also use resolveOnAbort to avoid storing unhandled promises

async function run();

const global = AbortSignal.timeout(10 * 1000)
using timeout = Signals.resolveOnAbort(global)

async function runWithTimeout() {
  const rejectOnAbort = timeout.get().then(() => { throw new Error("Aborted") })

  await Promise.race([run(), rejectOnAbort])
}