map-many

map each item of an iterable sequence to many items

Usage

package requires a system that supports async-iteration, either natively or via down-compiling

Install

npm install @async-generators/map-many --save
yarn add @async-generators/map-many

This package's main entry points to a commonjs distribution.

Additionally, the module entry points to a es2015 distribution, which can be used by build systems, such as webpack, to directly use es2015 modules.

Api

mapMany(source, selector)

mapMany() iterates the source and yields each item of iterable sequence returned by await selector(item, index)

source must have a [Symbol.asyncIterator] or [Symbol.iterator] property. If both are present only [Symbol.asyncIterator] is used.

selector(item, index) should return an iterable sequence. The second parameter is the index of the item as it appeared in the source sequence.

Example

example.js

const mapMany = require('@async-generators/map-many').default;

async function main() {
  async function* source() {
    yield "John";
  }
  async function* greet(name) {
    yield "Hello"; yield name; 
  }
  for await (let item of mapMany(source(), (x)=>greet(x))) {
    console.log(item);
  }
}

main();

Execute with the latest node.js:

node --harmony-async-iteration example.js

output:

Hello 
John

Typescript

This library is fully typed and can be imported using:

import filter from '@async-generators/map-many');

It is also possible to directly execute your properly configured typescript with ts-node:

ts-node --harmony_async_iteration foo.ts