it-map

What is it-map?

The it-map npm package is a utility for transforming async iterables. It allows you to apply a mapping function to each item in an async iterable, similar to how Array.prototype.map works for arrays.

What are it-map's main functionalities?

Basic Mapping

This feature allows you to apply a simple mapping function to each item in an async iterable. In this example, each number yielded by the async generator is doubled.

const itMap = require('it-map');

async function* asyncGenerator() {
  yield 1;
  yield 2;
  yield 3;
}

const mapped = itMap(asyncGenerator(), x => x * 2);

(async () => {
  for await (const value of mapped) {
    console.log(value); // 2, 4, 6
  }
})();

Async Mapping Function

This feature allows you to use an async function as the mapping function. In this example, each number is doubled after a 100ms delay.

const itMap = require('it-map');

async function* asyncGenerator() {
  yield 1;
  yield 2;
  yield 3;
}

const mapped = itMap(asyncGenerator(), async x => {
  await new Promise(resolve => setTimeout(resolve, 100));
  return x * 2;
});

(async () => {
  for await (const value of mapped) {
    console.log(value); // 2, 4, 6
  }
})();

Other packages similar to it-map

it-pipe

The it-pipe package is used for creating pipelines of async iterables. It allows you to compose multiple transformations in a readable manner. Compared to it-map, it-pipe provides a more comprehensive solution for chaining multiple async iterable transformations.

it-filter

The it-filter package is used for filtering items in async iterables. While it-map focuses on transforming each item, it-filter focuses on including or excluding items based on a predicate function. Both can be used together for more complex async iterable manipulations.

it-take

The it-take package is used for taking a specified number of items from an async iterable. This is useful for limiting the number of items processed, which can be combined with it-map for more controlled transformations.

README

it-map

Maps the values yielded by an async iterator

About

Convert one value from an (async)iterator into another.

Example

import map from 'it-map'

// This can also be an iterator, generator, etc
const values = [0, 1, 2, 3, 4]

const result = map(values, (val, index) => val++)

console.info(result) // [1, 2, 3, 4, 5]

Async sources and transforms must be awaited:

import map from 'it-map'

const values = async function * () {
  yield * [0, 1, 2, 3, 4]
}

const result = await map(values(), async (val, index) => val++)

console.info(result) // [1, 2, 3, 4, 5]

Install

$ npm i it-map

Browser <script> tag

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

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

API Docs

• https://achingbrain.github.io/it/modules/it_map.html

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.