gaearon

If you use server rendering, keep in mind that neither useLayoutEffect nor useEffect can run until the JavaScript is downloaded.

You might see a warning if you try to useLayoutEffect on the server. Here's two common ways to fix it.

Option 1: Convert to useEffect

If this effect isn't important for first render (i.e. if the UI still looks valid before it runs), then useEffect instead.

function MyComponent() {

bvaughn

The MIT License (MIT)

Copyright © <year> <copyright holders>

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

bvaughn

React recently introduced an experimental profiler API. This page gives instructions on how to use this API in a production release of your app.

Table of Contents

• Profiling in production
  • Create React App
  • Webpack 4

Profiling in production

React DOM automatically supports profiling in development mode for v16.5+, but since profiling adds some small additional overhead it is opt-in for production mode. This gist explains how to opt-in.

gaearon

In production, it is recommended to minify any JavaScript code that is included with your application. Minification can help your website load several times faster, especially as the size of your JavaScript source code grows.

Here's one way to set it up:

1. Install Node.js
2. Run npm init -y in your project folder (don't skip this step!)
3. Run npm install terser

Now, to minify a file called like_button.js, run in the terminal:

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.

sebmarkbage

The Rules of React

All libraries have subtle rules that you have to follow for them to work well. Often these are implied and undocumented rules that you have to learn as you go. This is an attempt to document the rules of React renders. Ideally a type system could enforce it.

What Functions Are "Pure"?

A number of methods in React are assumed to be "pure".

On classes that's the constructor, getDerivedStateFromProps, shouldComponentUpdate and render.

acdlite

Demo: Coordinating async React with non-React views

tl;dr I built a demo illustrating what it might look like to add async rendering to Facebook's commenting interface, while ensuring it appears on the screen simultaneous to the server-rendered story.

A key benefit of async rendering is that large updates don't block the main thread; instead, the work is spread out and performed during idle periods using cooperative scheduling.

But once you make something async, you introduce the possibility that things may appear on the screen at separate times. Especially when you're dealing with multiple UI frameworks, as is often the case at Facebook.

How do we solve this with React?

gaearon

/**
 * Stores are just seed + reduce function.
 * Notice they are plain objects and don't own the state.
 */
const countUpStore = {
  seed: {
    counter: 0
  },

  reduce(state, action) {

sebmarkbage

import { Component } from "React";

export var Enhance = ComposedComponent => class extends Component {
  constructor() {
    this.state = { data: null };
  }
  componentDidMount() {
    this.setState({ data: 'Hello' });
  }
  render() {

ryanflorence

Folder Structure

Please note

While this gist has been shared and followed for years, I regret not giving more background. It was originally a gist for the engineering org I was in, not a "general suggestion" for any React app.

Typically I avoid folders altogether. Heck, I even avoid new files. If I can build an app with one 2000 line file I will. New files and folders are a pain.