Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/ReactiveX/IxJS

The Interactive Extensions for JavaScript
https://github.com/ReactiveX/IxJS

Last synced: 3 months ago
JSON representation

The Interactive Extensions for JavaScript

Awesome Lists containing this project

README 

        
# The Interactive Extensions for JavaScript (IxJS)



[![Build Status](https://travis-ci.com/ReactiveX/IxJS.svg?branch=master)](https://travis-ci.com/ReactiveX/IxJS)

[![Build status](https://ci.appveyor.com/api/projects/status/dfuqvf29l477m54k/branch/master?svg=true)](https://ci.appveyor.com/project/mattpodwysocki/ixjs/branch/master)

[![npm version](https://badge.fury.io/js/ix.svg)](https://badge.fury.io/js/ix)

[![Join the chat at https://gitter.im/ReactiveXIxJS/](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/ReactiveXIxJS/?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)



*IxJS is a set of libraries to compose synchronous and asynchronous collections and [Array#extras](https://docs.microsoft.com/en-us/archive/blogs/ie/ecmascript-5-part-2-array-extras) style composition in JavaScript*



The Interactive Extensions for JavaScript (IxJS) brings the Array#extras combinators to iterables, generators, async iterables and async generators.  With the introduction of the `Symbol.iterator` and generators in ES2015, and subsequent introduction of `Symbol.asyncIterator` and async generators, it became obvious we need an abstraction over these data structures for composition, querying and more.



IxJS unifies both synchronous and asynchronous pull-based collections, just as RxJS unified the world of push-based collections.  RxJS is great for event-based workflows where the data can be pushed at the rate of the producer, however, IxJS is great at I/O operations where you as the consumer can pull the data when you are ready.



## Install [IxJS from npm](https://www.npmjs.com/package/ix)



```sh

npm install ix

```



(also read about how we [package IxJS](#packaging) below)



## `Iterable`



The `Iterable` class a way to create and compose synchronous collections much like Arrays, Maps and Sets in JavaScript using the Array#extras style using the familiar methods you are used to like `map`, `filter`, `reduce` and more.  We can use the [`for ... of`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of) statements to iterate our collections.



```js

// ES

import { from } from 'ix/iterable';

import { filter, map } from 'ix/iterable/operators';



// CommonJS

const from = require('ix/iterable').from;

const { filter, map } = require('ix/iterable/operators');



const source = function* () {

  yield 1;

  yield 2;

  yield 3;

  yield 4;

};



const results = from(source()).pipe(

  filter(x => x % 2 === 0),

  map(x => x * x)

);



for (let item of results) {

  console.log(`Next: ${item}`);

}



// Next 4

// Next 16

```



In addition, we also supply a `forEach` so it's your choice for which to use.



```js

// ES

import { from } from 'ix/asynciterable';

import { filter, map } from 'ix/asynciterable/operators';



// CommonJS

const from = require('ix/asynciterable').from;

const { filter, map } = require('ix/asynciterable/operators');



const source = function* () {

  yield 1;

  yield 2;

  yield 3;

  yield 4;

};



const results = from(source()).pipe(

  filter(x => x % 2 === 0),

  map(x => x * x)

);



results

  .forEach(item => {

    console.log(`Next: ${item}`);

  });

// Next 4

// Next 16

```



Instead of bringing in the entire library for `Iterable`, we can pick and choose which operators we want, for bundling concerns and add them directly to the `Iterable` prototype.



```js

// ES

import { IterableX as Iterable } from 'ix/iterable';

import 'ix/add/iterable/of';

import 'ix/add/iterable-operators/map';



// CommonJS

const { IterableX: Iterable } = require('ix/iterable');

require('ix/add/iterable/of');

require('ix/add/iterable-operators/map');



const results = Iterable.of(1,2,3)

  .map(x => x + '!!');

```



The `Iterable` object implements the iterator pattern in JavaScript by exposing the `[Symbol.iterator]` method which in turn exposes the `Iterator` class.  The iterator yields values by calling the `next()` method which returns the `IteratorResult` class.



```typescript

interface Iterable {

  [Symbol.iterator](): Iterator;

}



interface Iterator {

  next(value?: any): IteratorResult;

  return?(value?: any): IteratorResult;

  throw?(e?: any): IteratorResult;

}



interface IteratorResult {

  value: T;

  done: Boolean;

}

```



## `AsyncIterable`



The `AsyncIterable` object is based off the ECMAScript Proposal for [Asynchronous Iterators](https://github.com/tc39/proposal-async-iteration).  This would allow us to create asynchronous collections of Promises and be able to use such methods as the `map`, `filter`, `reduce` and other operators we can import.  Much like with the `Iterable` object where we can iterate through our collections, we can use `for await ... of` instead which allows us to iterate over the asynchronous collection.



```js

// ES

import { from } from 'ix/asynciterable';

import { filter, map } from 'ix/asynciterable/operators';



// CommonJS

const from = require('ix/asynciterable').from;

const { filter, map } = require('ix/asynciterable/operators');



const source = async function* () {

  yield 1;

  yield 2;

  yield 3;

  yield 4;

};



const results = from(source()).pipe(

  filter(async x => x % 2 === 0),

  map(async x => x * x)

);



for await (let item of results) {

  console.log(`Next: ${item}`);

}



// Next 4

// Next 16

```



Alternatively, we can use the built-in `forEach` and `catch` should there be any errors:



```js

// ES

import { from } from 'ix/asynciterable';

import { filter, map } from 'ix/asynciterable/operators';



// CommonJS

const from = require('ix/asynciterable').from;

const { filter, map } = require('ix/asynciterable/operators');



const source = async function* () {

  yield 1;

  yield 2;

  yield 3;

  yield 4;

};



const results = from(source()).pipe(

  filter(async x => x % 2 === 0),

  map(async x => x * x)

);



results

  .forEach(item => {

    console.log(`Next: ${item}`);

  })

  .catch(err => {

    console.log(`Error ${err}`);

  });



for await (let item of results) {

  console.log(`Next: ${item}`);

}



// Next 4

// Next 16

```



Instead of bringing in the entire library for `AsyncIterable`, we can pick and choose which operators we want, for bundling concerns directly to the `AsyncIterable` prototype.



```js

// ES

import { AsyncIterableX as AsyncIterable } from 'ix/asynciterable';

import 'ix/add/async-iterable/of';

import 'ix/add/asynciterable-operators/map';



// CommonJS

const { AsyncIterableX: AsyncIterable } = require('ix/asynciterable');

require('ix/add/asynciterable-operators/map');



const results = AsyncIterable.of(1,2,3)

  .map(x => x + '!!');

```



The `AsyncIterable` class implements the async iterator pattern in JavaScript by exposing the `[Symbol.asyncIterator]` method which in turn exposes the `AsyncIterator` class.  The iterator yields values by calling the `next()` method which returns a Promise which resolves a `IteratorResult` class.



```typescript

interface AsyncIterable {

  [Symbol.asyncIterator](): AsyncIterator;

}



interface AsyncIterator {

  [Symbol.asyncIterator](): AsyncIterator;

  next(value?: any): Promise>;

  return?(value?: any): Promise>;

  throw?(e?: any): Promise>;

}



interface IteratorResult {

  value: T;

  done: Boolean;

}

```



## Converting from Iterable to AsyncIterable



Using IxJS, you can easily go from an `Iterable` to an `AsyncIterable` using a number of methods.  First, we can use the `from` function, either as a standalone or on the `Ix.AsyncIterable` object.  The `from` method accepts a standard `Iterable`, `Generator`, and `Iterator` of Promises, or even another `AsyncIterable`.



```js

import { from } from 'ix/asynciterable';

import { map } from 'ix/asynciterable/operators';



const xs = [1, 2, 3, 4];

const mapped = from(xs).pipe(

  map(async (item, index) => item * index)

);



for await (let item of mapped) {

  console.log(`Next: ${item}`);

}



// Next 0

// Next 2

// Next 6

// Next 12

```



## Contributing



We are grateful for contributions to the IxJS project.  The IxJS project evolves because of community involvement from people such as yourselves.  Please read below on how to get involved.



### [Code Of Conduct](CODE_OF_CONDUCT.md)



The IxJS project has a strict Code of Conduct that must be adhered at all times.  This code of conduct comes from the [Contributor Convenant](http://contributor-covenant.org/).  Please read [the full text](CODE_OF_CONDUCT.md) as to what is and is not permitted.



### Contributing Guide



Read the [Contributing Guide](CONTRIBUTING.md) on how to get involved with the IxJS project.  This includes our development process and how to test your code before committing.



### Packaging



`IxJS` is written in TypeScript, but the project is compiled to multiple JS versions and common module formats. The base IxJS package includes all the compilation targets for convenience, but if you're conscientious about your node_modules footprint, don't worry -- we got you. The targets are also published under the @reactivex namespace:



```sh

npm install @reactivex/ix-ts # TypeScript target

npm install @reactivex/ix-es5-cjs # ES5 CommonJS target

npm install @reactivex/ix-es5-esm # ES5 ESModules target

npm install @reactivex/ix-es5-umd # ES5 UMD target

npm install @reactivex/ix-es2015-cjs # ES2015 CommonJS target

npm install @reactivex/ix-es2015-esm # ES2015 ESModules target

npm install @reactivex/ix-es2015-umd # ES2015 UMD target

npm install @reactivex/ix-esnext-cjs # ESNext CommonJS target

npm install @reactivex/ix-esnext-esm # ESNext ESModules target

npm install @reactivex/ix-esnext-umd # ESNext UMD target

```



### Why we package like this



The JS community is a diverse group with a varied list of target environments and tool chains. Publishing multiple packages accommodates projects of all types. Friends targeting the latest JS runtimes can pull in the ESNext + ESM build. Friends needing wide browser support and small download size can use the UMD bundle, which has been run through Google's Closure Compiler with advanced optimizations.



If you think we missed a compilation target and it's a blocker for adoption, please open an issue. We're here for you ❤️.



## License



The MIT License (MIT)



Copyright (c) ReactiveX



Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:



The above copyright notice and this permission notice shall be included in all

copies or substantial portions of the Software.



THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

SOFTWARE.