erhangundogan

mikowl

// Inspired by https://twitter.com/coderitual/status/1112297299307384833 and https://tapajyoti-bose.medium.com/7-killer-one-liners-in-javascript-33db6798f5bf

//  Remove any duplicates from an array of primitives.
const unique = [...new Set(arr)]

// Sleep in async functions. Use: await sleep(2000).
const sleep = (ms) => (new Promise(resolve => setTimeout(resolve, ms)));
// or
const sleep = util.promisify(setTimeout);

joeytwiddle

Do not use forEach with async-await

TLDR: Use for...of instead of forEach() in asynchronous code.

For legacy browsers, use for...i or [].reduce()

To execute the promises in parallel, use Promise.all([].map(...))

The problem

gaearon

Note:

When this guide is more complete, the plan is to move it into Prepack documentation.
For now I put it out as a gist to gather initial feedback.

A Gentle Introduction to Prepack (Part 1)

If you're building JavaScript apps, you might already be familiar with some tools that compile JavaScript code to equivalent JavaScript code:

• Babel lets you use newer JavaScript language features, and outputs equivalent code that targets older JavaScript engines.

chrisjpatty

const maskDate = value => {
  let v = value.replace(/\D/g,'').slice(0, 10);
  if (v.length >= 5) {
    return `${v.slice(0,2)}/${v.slice(2,4)}/${v.slice(4)}`;
  }
  else if (v.length >= 3) {
    return `${v.slice(0,2)}/${v.slice(2)}`;
  }
  return v
}

stevekinney

State Management Patterns

Repositories

Download the following repositories and run yarn install in each:

• Basic Counter
• Pizza Calculator
• Jetsetter
• Offices and Dragons

joe-schorn

const request = require("request");
const EventEmitter = require("events").EventEmitter;
const util = require("util");

const endpoint = "https://discordapp.com/api/";

function DiscordWebhook(url) {
  this.url = url;
  this.onReady = false;
  var queue = [];

levibostian

Today, single page web apps are driving many websites that we use each and every day. Instead of having your browser request a new web page for each and every action you perform on a web page, single page web apps may load all in one request to smoothly and quickly transition with every action you perform.

When building single page web apps, you may decide to retrieve all of the HTML, CSS and Javascript with one single page load or dynamically load these resources as the user moves about your site. Either way, it can be a pain to bundle all of these assets together for the end user to download from your web server. This is where webpack comes into play.

webpack does all of the heavy lifting bundling all of your HTML, CSS and Javascript together. If you write your site all from scratch or depend on dependencies from npm, webpack takes care of packaging it all together for you. It has the ability to take your single page web app, cut out all of the code you don't need, then packa

joepie91

Important warning

You should almost never actually use this. The same applies to fs.stat (when used for checking existence).

Checking whether a file exists before doing something with it, can lead to race conditions in your application. Race conditions are extremely hard to debug and, depending on where they occur, they can lead to data loss or security holes. Using the synchronous versions will not fix this.

Generally, just do what you want to do, and handle the error if it doesn't work. This is much safer.

• If you want to check whether a file exists, before reading it: just try to open the file, and handle the ENOENT error when it doesn't exist.
• If you want to make sure a file doesn't exist, before writing to it: open the file using an exclusive mode, eg. wx or ax, and handle the error when the file already exists.

chantastic

Hi Nicholas,

I saw you tweet about JSX yesterday. It seemed like the discussion devolved pretty quickly but I wanted to share our experience over the last year. I understand your concerns. I've made similar remarks about JSX. When we started using it Planning Center, I led the charge to write React without it. I don't imagine I'd have much to say that you haven't considered but, if it's helpful, here's a pattern that changed my opinion:

The idea that "React is the V in MVC" is disingenuous. It's a good pitch but, for many of us, it feels like in invitation to repeat our history of coupled views. In practice, React is the V and the C. Dan Abramov describes the division as Smart and Dumb Components. At our office, we call them stateless and container components (view-controllers if we're Flux). The idea is pretty simple: components can't