...is a set of libraries to compose synchronous and asynchronous collections and Array#extras style composition in JavaScript
The Interactive Extensions for JavaScript (IxJS) is a library for creating and composing asynchronous sequences using both the Iterable
and AsyncIterable
classes.
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.
const Iterator = require('ix').Iterator;
Iterator.from([1,2,3,4])
.filter(x => x % 2 === 0)
.map(x => x * 2)
.forEach(x => console.log(`Next ${x}`));
// => 4
// => 8
The Iterable
class 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.
interface Iterable<T> {
[Symbol.iterator](): Iterator<T>;
}
interface Iterator<T> {
[Symbol.iterator](): Iterator<T>;
next(): IteratorResult<T>;
}
interface IteratorResult<T> {
value: T;
done: Boolean;
}
The AsyncIterator
class is based off the ECMAScript Proposal for Asynchronous Iterators. This would allow us to create asynchronous collections of Promises and be able to use such methods as the map
, filter
, reduce
and other Array#extras methods that you are used to using.
const AsyncIterable = require('ix').AsyncIterable;
async function *gen() {
yield Promise.resolve(1);
yield Promise.resolve(2);
yield Promise.resolve(3);
yield Promise.resolve(4);
}
AsyncIterable.from(gen())
.filter(x => x % 2 === 0)
.map(x => x * 2)
.forEachAsync(x => console.log(`Next ${x}`))
.catch(err => console.log(`Error ${err}`));
// => 4
// => 8
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.
interface AsyncIterable<T> {
[Symbol.asyncIterator](): AsyncIterator<T>;
}
interface Iterator<T> {
[Symbol.asyncIterator](): Iterator<T>;
next(value): Promise<IteratorResult<T>>;
[optional] throw(value): Promise<IteratorResult<T>>;
[optional] return(value): Promise<IteratorResult<T>>;
}
interface IteratorResult<T> {
value: T;
done: Boolean;
}
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.
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