ljharb

Array Iteration

https://gist.github.com/ljharb/58faf1cfcb4e6808f74aae4ef7944cff

While attempting to explain JavaScript's reduce method on arrays, conceptually, I came up with the following - hopefully it's helpful; happy to tweak it if anyone has suggestions.

Intro

JavaScript Arrays have lots of built in methods on their prototype. Some of them mutate - ie, they change the underlying array in-place. Luckily, most of them do not - they instead return an entirely distinct array. Since arrays are conceptually a contiguous list of items, it helps code clarity and maintainability a lot to be able to operate on them in a "functional" way. (I'll also insist on referring to an array as a "list" - although in some languages, List is a native data type, in JS and this post, I'm referring to the concept. Everywhere I use the word "list" you can assume I'm talking about a JS Array) This means, to perform a single operation on the list as a whole ("atomically"), and to return a new list - thus making it mu

mhevery

Zone Motivation

Make writing asynchronous code easier by having a consistent way of propagating "context" across related asynchronous operations. Have the "context" be responsible for async-local-storage, allowing the execution before and after hooks, and "context"-local error handling. Finally make sure that the "context"s are composable.

This feature needs to be part of the platform so that library and framework authors can relay on a common well know API, otherwise adoption will be limited.

jlongster

A lot of people mentioned other immutable JS libraries after reading my post. I thought it would be good to make a list of available ones.

There are two types of immutable libraries: simple helpers for copying JavaScript objects, and actual persistent data structure implementations. My post generally analyzed the tradeoffs between both kinds of libraries and everything applies to the below libraries in either category.

Libraries are sorted by github popularity.

Persistent Data Structures w/structural sharing

benatkin

// Place user-specific overrides in this file, to ensure they're preserved
// when upgrading
{
  "folder_exclude_patterns": [".svn", ".git", ".hg", "CVS", "node_modules"]
}

sebmarkbage

var Bar1 = base => class extends base {
  componentWillMount(){
    super.componentWillMount();
    console.log('Bar1');
  }
};

var Bar2 = base => class extends base {
  componentWillMount(){
    super.componentWillMount();

ebidel

<!-- 
Complete feature detection for ES modules. Covers:

1. Static import: import * from './foo.js';
2. Dynamic import(): import('./foo.js').then(module => {...});

Demo: http://jsbin.com/tilisaledu/1/edit?html,output

Thanks to @_gsathya, @kevincennis, @rauschma, @malyw for the help.
-->

tilomitra

var scrollView = new Y.ScrollView({
    srcNode: '#resultList',
    height: 260,
    flick: {
        minDistance:1,
        minVelocity:0.4,
        axis: "y"
    },
    deceleration: 0.983,
    bounce:0.65,		

domenic

// Dynamic module loading using runtime-composed strings, decisions, etc.

for (const m of ["cool", "awesome", "fun", "whee"]) {
  if (Math.random() > 0.5) {
    importModule(`/js/${m}.js`).then(
      module => console.log("Module instance object for " + m, module),
      e => console.error(e)
    );
  }
}

WebReflection

// this is now a module:
// https://github.com/WebReflection/backtick-template#es2015-backticks-for-es3-engines--


var template = require('backtick-template');

// just string
const info = 'template';
`some ${info}` === template('some ${info}', {info});

samthor

import fs from 'fs';

// as per https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/master/CSSModules/v1Explainer.md
export default function cssModules() {
  return {
    name: 'css-modules',

    async load(id) {
      if (!id.endsWith('.css')) {
        return;