abortable-iterator
TypeScript icon, indicating that this package has built-in type declarations

5.0.1 • Public • Published

abortable-iterator

codecov CI

Make any iterator or iterable abortable via an AbortSignal

Table of contents

Install

$ npm i abortable-iterator

Browser <script> tag

Loading this module through a script tag will make it's exports available as AbortableIterator in the global namespace.

<script src="https://unpkg.com/abortable-iterator/dist/index.min.js"></script>

The AbortController is used in the fetch API to abort in flight requests from, for example, a timeout or user action. The same concept is used here to halt iteration of an async iterator.

Usage

import { abortableSource } from 'abortable-iterator'

// An example function that creates an async iterator that yields an increasing
// number every x milliseconds and NEVER ENDS!
const asyncCounter = async function * (start, delay) {
  let i = start
  while (true) {
    yield new Promise(resolve => setTimeout(() => resolve(i++), delay))
  }
}

// Create a counter that'll yield numbers from 0 upwards every second
const everySecond = asyncCounter(0, 1000)

// Make everySecond abortable!
const controller = new AbortController()
const abortableEverySecond = abortableSource(everySecond, controller.signal)

// Abort after 5 seconds
setTimeout(() => controller.abort(), 5000)

try {
  // Start the iteration, which will throw after 5 seconds when it is aborted
  for await (const n of abortableEverySecond) {
    console.log(n)
  }
} catch (err) {
  if (err.code === 'ERR_ABORTED') {
    // Expected - all ok :D
  } else {
    throw err
  }
}

API

import {
  abortableSource,
  abortableSink,
  abortableTransform,
  abortableDuplex
} from 'abortable-iterator'

abortableSource(source, signal, [options])

(alias for abortable.source(source, signal, [options]))

Make any iterator or iterable abortable via an AbortSignal.

Parameters

Name Type Description
source Iterable|Iterator The iterator or iterable object to make abortable
signal AbortSignal Signal obtained from AbortController.signal which is used to abort the iterator.
options Object (optional) options
options.onAbort Function An (async) function called when the iterator is being aborted, before the abort error is thrown. Default null
options.abortMessage String The message that the error will have if the iterator is aborted. Default "The operation was aborted"
options.abortCode String|Number The value assigned to the code property of the error that is thrown if the iterator is aborted. Default "ABORT_ERR"
options.returnOnAbort Boolean Instead of throwing the abort error, just return from iterating over the source stream.
options.onReturnError Function When a generator is aborted, we call .return on it - if this function errors the error value will be passed to the .onReturnError callback if passed. Default null

Returns

Type Description
Iterable An iterator that wraps the passed source parameter that makes it abortable via the passed signal parameter.

The returned iterator will throw an AbortError when it is aborted that has a type with the value aborted and code property with the value ABORT_ERR by default.

abortableSink(sink, signal, [options])

The same as abortable.source except this makes the passed sink abortable. Returns a new sink that wraps the passed sink and makes it abortable via the passed signal parameter.

abortableTransform(transform, signal, [options])

The same as abortable.source except this makes the passed transform abortable. Returns a new transform that wraps the passed transform and makes it abortable via the passed signal parameter.

abortableDuplex(duplex, signal, [options])

The same as abortable.source except this makes the passed duplex abortable. Returns a new duplex that wraps the passed duplex and makes it abortable via the passed signal parameter.

Note that this will abort both sides of the duplex. Use duplex.sink = abortable.sink(duplex.sink) or duplex.source = abortable.source(duplex.source) to abort just the sink or the source.

Related

  • it-pipe Utility to "pipe" async iterables together

Contribute

Feel free to dive in! Open an issue or submit PRs.

API Docs

License

Licensed under either of

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Package Sidebar

Install

npm i abortable-iterator

Weekly Downloads

26,148

Version

5.0.1

License

Apache-2.0 OR MIT

Unpacked Size

32 kB

Total Files

13

Last publish

Collaborators

  • achingbrain
  • alanshaw