npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

axax

v0.2.2

Published

A library of async iterator extensions for JavaScript including ```map```, ```reduce```, ```filter```, ```flatMap```, ```pipe``` and [more](https://github.com/jamiemccrindle/axax/blob/master/docs/API.md#functions).

Downloads

41,976

Readme

Async Iterator Extensions

A library of async iterator extensions for JavaScript including map, reduce, filter, flatMap, pipe and more.

Installation

npm install axax # or yarn add axax

Why Axax?

Async iterators are a useful way to handle asynchronous streams. This library adds a number of utility methods similar to those found in lodash, underscore, Ramda or RxJs.

es5 vs esnext

Axax contains both transpiled es5 code as well as esnext code, the difference being that esnext uses the native for await syntax. In nodejs 10.x that gives approximately a 40% speedup.

// use es5 if you want to support more browsers
import { map } from "axax/es5/map"; 

// use esnext if you're only using node 10.x or supporting very new browsers
import { map } from "axax/esnext/map"; 

Reference Documentation

Examples

fromEvent

fromEvent turns DOM events into an iterable.

import { fromEvent } from "axax/es5/fromEvent";

const clicks = fromEvent(document, 'click');

for await (const click of clicks) {
    console.log('a button was clicked');
}

pipe, map, filter, fromLineReader

fromLineReader turns a NodeJS LineReader into an async iterable. The example below prints the lines from a file in upper case after filtering out the empty ones.

// create the line reading async iterable
const lines = fromLineReader(
    require("readline").createInterface({
        input: require("fs").createReadStream("./data/example.txt")
    })
);

// create a filter that removes empty lines
const notEmpty = filter(line => line.length > 0);

// convert to uppercase
const toUpperCase = map(line => line.toUpperCase());

// go through each of the non empty lines
for await (const line of pipe(notEmpty, toUpperCase)(lines)) {
    console.log(line);
}

Subject

Subject makes it easy to turn stream of events into an iterable. The code below is essentially how fromEvent was implemented.

import { Subject } from "axax/es5/subject";

const subject = new Subject();

// set up a callback that calls value on the subject
const callback = value => subject.onNext(value);

// attach the callback to the click event
document.addEventListener('click', callback);

// remove the callback when / if the iterable stops
subject.finally(() => document.removeEventListener('click', callback));

// go through all the click events
for await (const click of subject.iterator) {
    console.log('a button was clicked');
}

Avoiding leaks

It's possible to have an async iterator leak if it never returns a value e.g.:

const subject1 = new Subject();
const subject2 = new Subject();

async function* neverEnds() {
  try {
    for await(const i of subject2.iterator) {
      yield i;
    }
  } finally {
    console.log("never called")
  }
}

async function* run() {
  for await(const i of merge(subject1.iterator,neverEnds())) {
    break;
  }
}

run()
subject1.onNext(1)

If you need to be able to cancel async iterators that may never return values, consider Rx or regular Observables for now.

(Thanks to @awto for the example)