Dan Abramov gaearon

## uselayouteffect-ssr.md

      
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                gaearon
                / uselayouteffect-ssr.md
            
            
              Last active May 24, 2019
            
              
                useLayoutEffect and server rendering
              
          
      View uselayouteffect-ssr.md
  
    
    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() {

  
## MyResponsiveComponent.js
function MyResponsiveComponent() {
  const width = useWindowWidth(); // Our custom Hook
  return (
    <p>Window width is {width}</p>
  );
}

## npm_init_error.md

      
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                gaearon
                / npm_init_error.md
            
            
              Created Jun 28, 2018
            
              
                What to do when npm init -y fails
              
          
      View npm_init_error.md
  
    
    If you get an "Invalid name" error when you run npm init -y, rename the project folder to only contain lowercase ASCII letters or hyphens (e.g. my-project), and try again.

  
## index.html
<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>Add React in One Minute</title>
  </head>
  <body>

    <h2>Add React in One Minute</h2>
    <p>This page demonstrates using React with no build tooling.</p>

## like_button.js
'use strict';

class LikeButton extends React.Component {
  constructor(props) {
    super(props);
    this.state = { liked: false };
  }

  render() {
    if (this.state.liked) {

## minification.md

      
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                gaearon
                / minification.md
            
            
              Last active May 19, 2019
            
              
                How to Set Up Minification
              
          
      View minification.md
  
    
    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:

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

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

  
## index.html
<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>Add React in One Minute</title>
  </head>
  <body>

    <h2>Add React in One Minute</h2>
    <p>This page demonstrates using React with no build tooling.</p>

## LikeButton.js
'use strict';

const e = React.createElement;

class LikeButton extends React.Component {
  constructor(props) {
    super(props);
    this.state = { liked: false };
  }

## modern_js.md

      
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                gaearon
                / modern_js.md
            
            
              Last active May 21, 2019
            
              
                Modern JavaScript in React Documentation
              
          
      View modern_js.md
  
    
    If you haven’t worked with JavaScript in the last few years, these three points should give you enough knowledge to feel comfortable reading the React documentation:

We define variables with let and const statements. For the purposes of the React documentation, you can consider them equivalent to var.
We use the class keyword to define JavaScript classes. There are two things worth remembering about them. Firstly, unlike with objects, you don't need to put commas between class method definitions. Secondly, unlike many other languages with classes, in JavaScript the value of this in a method [depends on how it is called](https://developer.mozilla.org/en-US/docs/Web/Jav


## prepack-gentle-intro-1.md

      
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                gaearon
                / prepack-gentle-intro-1.md
            
            
              Last active May 15, 2019
            
              
                A Gentle Introduction to Prepack, Part 1
              
          
      View prepack-gentle-intro-1.md
  
    
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.