@jsenv/abort

Abort

Help to write code accepting an abortSignal.

• API designed to properly cleanup things (event listeners, timeouts, ...)
  • Prevents memory leak
  • No maxListeners warning for "abort" event on Node.js
• Manage multiple abort signals
  • Compose abort signals from multiple sources
  • Code can react differently according to which signal aborted the operation
• Allow to bypass safely max listeners warning when a single signal NEEDS to be listened lot of times
  • No "potential memory leak" when code does 20 http requests in parallel

Example

fetch_demo.mjs

import { customFetch } from "./fetch_custom.mjs"

const abortController = new AbortController()
const signal = abortController.signal
process.on("warning", () => {
  abortController.abort()
})
await customFetch("http://example.com", { signal })

The code above forwards an abort signal to customFetch. Code below shows how "@jsenv/abort" helps to manage the received signal.

fetch_custom.mjs

export const customFetch = (
  url,
  { signal = new AbortController().signal } = {},
) => {
  // create an operation
  const fetchOperation = Abort.startOperation()

  // abort according to signal received in param
  fetchOperation.addAbortSignal(signal)

  // also abort on SIGINT
  const SIGINTAbortSource = fetchOperation.addAbortSource((abort) => {
    process.on("SIGINT", abort)
    return () => {
      process.removeListener("SIGINT", abort)
    }
  })

  // also abort after 5s
  const timeoutAbortSource = fetchOperation.timeout(5000)

  try {
    const response = await fetch(url, { signal })
    return response
  } catch (e) {
    if (SIGINTAbortSource.signal.aborted) {
      // aborted by SIGINT
    }
    if (timeoutAbortSource.signal.aborted) {
      // aborted by timeout
    }
    if (signal.aborted) {
      // aborted from outside
    }
    throw e
  }
}

Installation

npm install @jsenv/abort