it-parallel

it-parallel

Takes an (async) iterable that emits promise-returning functions, invokes them in parallel up to the concurrency limit and emits the results as they become available, optionally in the same order as the input

Table of contents

• Install
  • Browser <script> tag
• Usage
• License
• Contribution

Install

$ npm i it-parallel

Browser <script> tag

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

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

Usage

import parallel from 'it-parallel'
import all from 'it-all'
import delay from 'delay'

// This can also be an iterator, async iterator, generator, etc
const input = [
  async () => {
    console.info('start 1')
    await delay(500)

    console.info('end 1')
    return 1
  },
  async () => {
    console.info('start 2')
    await delay(200)

    console.info('end 2')
    return 2
  },
  async () => {
    console.info('start 3')
    await delay(100)

    console.info('end 3')
    return 3
  }
]

const result = await all(parallel(input, {
  concurrency: 2
}))

// output:
// start 1
// start 2
// end 2
// start 3
// end 3
// end 1

console.info(result) // [2, 3, 1]

If order is important, pass ordered: true as an option:

const result = await all(parallel(input, {
  concurrency: 2,
  ordered: true
}))

// output:
// start 1
// start 2
// end 2
// start 3
// end 3
// end 1

console.info(result) // [1, 2, 3]

License

Licensed under either of

• Apache 2.0, (LICENSE-APACHE / http://www.apache.org/licenses/LICENSE-2.0)
• MIT (LICENSE-MIT / http://opensource.org/licenses/MIT)

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.