Table of Contents
-
Awesome React Ecosystem
- Code Along Edition
- Easy start React
- Who this book is for
- Development environment
- Why React is awesome
- Why read React Speed Coding
- Prior art
- Stakeholder perspectives on speed
- Who is using React
- Technology stack
- Measuring speed
- Why learn React comparing with Angular
- Shared learning path between Angular 2 and React
- Setup React Webpack
-
ES6 React Guide
- Hello World React
- Component composition and naming
- Files and folder structure
- Root component index.jsx
- Module import
- World.jsx component
- Class definition
- Constructor
- Event Handlers and setState
- JSX and the render method
- Template literals and ternary conditionals
- Properties
- Event UI binding
- Controlled components
- PropTypes and defaultProps
- ES7 Property Initializers
- Complete World.jsx listing
- Hello.jsx stateless component
- Component styles in world.css
- Base styles in element.css
- Entry CSS using style.css
- Run development server
- React Chrome Extension
Awesome React Ecosystem
Welcome reader. The aim of this book is to get you from concept to coding real world React apps, as fast as possible.
React ecosystem is constantly evolving and changing at a fast pace. This book equips you to take the right decisions matching your project requirements with best practices, optimized workflows, and powerful tooling.
Code Along Edition
We are significantly revising this edition of React Speed Coding book.
- Adding new Code Along GitHub repository containing branches for code you complete in each chapter.
- Chapter by chapter demos are available at new demos website.
- Making each chapter stand on its own so you can complete a significant learning step at the end of each chapter.
- Ensuring that your learning path is as linear as possible, without too many cross-references due to refactoring of code we write in each chapter.
- The new edition also features better typography, color coding, and more screenshots to aid your learning.
- Upgrading to the latest development environment and dependencies as of this writing.
- Adding new sections to make your React journey faster, easier, and better.
- Reducing the code you write to achieve the same goals.
- Redesigning the UI CSS using Block, Element, Modifier method for more scalable, yet less verbose design.
- Several new custom components for Buttons, Forms, Layout, and other features.
Easy start React
If you want to dig into React coding right away, you can fast forward first four chapters in this book.
Getting started with React is now easier than ever. Get your first React app up and running in three easy steps. You may want to read the sample chapter titled Easy Start React from our new book React Eshop. We use Facebook’s Create React App scaffold generator to fast start into our first React app.
Go ahead give it a go. You will appreciate the magic behind the scenes as we learn to build a powerful development toolchain on similar lines as Facebook’s Create React App in this book. This will result in two benefits for our readers. First, you will learn about important React ecosystem technologies including Webpack, PostCSS, ESLint, and Babel in a step-by-step linear manner. Second, you will be able to easily extend apps generated using Create React App as you mature beyond the scaffolded code and the opinionated defaults used by Create React App.
Who this book is for
The React Speed Coding book assumes basic knowledge of programming in JavaScript, HTML, and CSS.
If you are a complete beginner, there is enough guidance available for you to make this your first programming primer with suggested additional reading.
Experienced web developers will master React component design workflow using latest ES6 language features. If you already program in React, you can use this book to optimize your development, testing, and production workflow.
Development environment
This book assumes you have access to a Mac, Linux, or a Cloud based editor offering virtual machine hosted development environment in your Web browser.
We will walk you through the entire React development environment setup from scratch.
While it is possible to run samples from this book using Windows, there are known issues in setting up Node and certain NPM packages.
As a safe alternative you can use any of the Cloud based code editors which offer Linux Development environment within the convenience of your web browser. You do not need to know how to use Linux to operate these web based editors. You can start with a generous free account with basic stack including Node.js already setup for you.
Cloud9 is our favorite web based code editor. Other options include Nitrous.
On Mac or Linux you can use your favorite code editor. This book is written using the open source Atom editor from the Github team. Atom gets you started coding by just dragging and dropping a folder onto the editor. You can then add power user features as you grow with Atom using custom packages, code snippets, among others.
Why React is awesome
Writing the React Speed Coding book, companion code, and the ReactSpeed.com demo website has been fun and fulfilling at the same time. Thanks to the amazing ecosystem that React and open source community have created in a relatively short span of time.
What we love about React and companion libraries like Redux is how they introduce constraints and flexibility at the same time. A very difficult goal to achieve when writing generic libraries and frameworks. React and Redux seem to have done so elegantly. Growing GitHub stars and cross-industry adoption is proof of this achievement.
To us React is about thinking in design and architectural patterns. It is more than making choices about which framework or library to use, or how to use these. We rapidly raise our thinking to design, requirements, solving real-world problems, that our apps are expected to address.
Learning React is about future proofing our investment more than any other framework or library with similar goals. Thanks to flexibility of integrating with React, even some of the competing frameworks offer integration paths with the React ecosystem. These include Meteor-React integration, Redux use cases with Angular, and TypeScript-React playing well together, just to name a few.
Most awesome aspect of learning React is that it is an ecosystem. It has a life of its own above and beyond Facebook, the original authors of React core. No wonder you see companies like Netflix, Airbnb, Kadira, Khan Academy, and Flipboard contributing their React libraries and tools to the open source.
Successfully navigating this growing ecosystem, making the right technology stack decisions along the way, will make the difference between an average programmer and a world-class designer-developer of the future. We sincerely hope React Speed Coding can contribute to your journey in mastering the React ecosystem of technologies.
Here’s to moving from Concept to Code to Cash, speedily!
Why read React Speed Coding
React Speed Coding enables you to optimize your React development workflow and speed up the app design lifecycle.
Setup React Webpack development environment complete with Node and Babel including development, testing, and production workflows. Production optimize Webpack development toolchain for CSS, JS, HTML pre-processing, faster builds, more performant code.
Learn ES6 React features including arrow functions, template literals, variable scoping, immutability, pure functions, among others.
Create complete single page app using Redux store, actions, and reducers.
Create custom React Speed UI library using Flexbox and PostCSS, with goals including responsive design, single page app components, ease of customization, reusable code, and high performance.
Apply Behavior-Driven Development techniques to create a comprehensive testing strategy for your apps. This includes ESLint and StyleLint to provide in-editor coding guidance on industry best practices for JavaScript and CSS. Use Mocha to describe specs. Chai for writing assertions. Sinon to spy on methods and events. We also learn about Enzyme for simple yet powerful React component level testing.
Adopt a comprehensive component design workflow including five strategies for s tarting component design by creating React components from embeds, REST APIs, samples, and wireframes.
Integrate your apps with serverless architecture using Firebase hosting. Create REST API for component design workflow using Firebase visual tools. Connect custom React components you create in this book with Firebase realtime database.
Run demo app and components live at ReactSpeed.com website.
Visit our popular GitHub repository to download and reuse source code from this book.
Prior art
The author would love to take the credit for coining the term “Speed Coding”. However, Speed Coding is based on very strong foundations and popular prior art.
Speed of Developer Workflow. Speed Coding follows some of the methods and tools as prescribed by the Lean Startup principles. See infographic for code faster, measure faster, learn faster.
Code faster principles we cover in this book include writing unit tests, continuos integration, incremental deployment, leveraging open source, cloud computing, refactoring, just-in-time scalability, and developer sandboxing.
Measure faster principles include usability tests, real-time monitoring, and search engine marketing.
Learn faster principles we apply in this book include smoke tests, split testing, and rapid prototyping.
Speed of Design. Speed Coding embraces the designer-developer evolution and also bases certain principles on the Design Thinking methodology and Visual Design principles.
We use these techniques in designing React Speed UI library using custom React components, PostCSS, Flexbox, and SVG.
Speed of Technology Decisions. Speed Coding technology stack is compared with industry best practice guidance including the awesome ThoughtWorks Technology Radar.
Technology Stack section, part of Introduction chapter, highlights React ecosystem technologies we cover in this book, in line with recommendations from the Radar.
The cover image for our book depicts NASA space shuttle lift-off and is representative of our central theme. The science of speed. We thank Pixabay for providing this NASA imagery in the Creative Commons.
Stakeholder perspectives on speed
In order to fulfill the promise of Speed Coding, we need to start by establishing some baselines. What are we speeding up? How are we measuring this speed? Why does it matter?
Let us start with the Why. Speed Coding is essential for three stakeholders. The user. The developer. The sponsor.
As app users we define speed mostly as performance and reactivity of the app. We even define speed as frequency of timely and desired updates to the apps we are using. Most importantly we define speed by time it takes to get things done.
As developers we define speed in terms of our development workflow. How long does it take to code, build, test, deploy, debug, and reactor. We also define speed of decision making relating to our development and technology stack.
As sponsors for an app project we define speed in terms of time to market. How long does it take to move from Concept to Code to Cash. Believe us, you first heard that phrase here, and we truly mean it!
Who is using React
Open sourced, developed, and used by Facebook and Instagram teams. React has also found wide adoption among leading technology, app, and digital companies.
- Airbnb are contributors of the popular React style guide.
- Atlassian redesigned their popular messaging app HipChat in React and Flux. They chose React because it is component based, declarative minus the bloat, uses Virtual DOM, relatively small library as opposed to full framework, simple, offers unidirectional data flow, and easily testable.
- BBC mobile homepage uses React.
- CloudFlare has active React projects on GitHub.
- Flipboard are authors of popular React Canvas.
- Khan Academy has several GitHub projects using React.
- Mapbox React Native module for creating custom maps.
- Netflix chooses React for startup speed of UI, runtime performance, and modularity it offers.
- Uber has several React GitHub projects including react-vis, a charting component library for React.
Technology stack
ThoughtWorks Technology Radar ranks technologies based on Adopt > Trial > Assess > Hold relative ranking. This is based on their own usage of these technologies across projects for leading enterprises globally. In terms of speed of decision making about your own technology stack, this is one tool that proves very helpful.
React Speed Coding will be addressing following technologies, platforms, techniques, frameworks, and tools.
ES6 (Adopt). JavaScript ECMAScript 6 is right at the top of the Radar list of languages and frameworks. We cover important concepts relevant for coding React in ES6.
React (Adopt). React is a close second on the Radar. Of course this book is all about React so we are well covered.
Redux and Flux (Trial). Redux is a new entrant on the Radar. We are dedicating an entire chapter and a relatively complex app for decent coverage of this important technology in React ecosystem. Flux is an architectural style recommended for React. Redux evolves ideas of Flux, avoiding its complexity, according to the author of Redux.
React Native (Trial). Another entry high on the Radar from React ecosystem. We are covering Flexbox which is one of the key technologies in React Native stack. Of course React and Redux make up the mix.
GraphQL (Assess). Another up and coming technology in React stack. GraphQL is an alternative to REST protocol. Goes hand in hand with Relay, another technology from the Facebook camp.
Immutable.js (Assess). Yet another Facebook open source project. Goes well with Redux.
Recharts (Assess). Integrates D3 charts and React. We will implement samples using Rumble Charts, a popular alternative, in this book.
Browsersync (Trial). Browsersync is a great time-saver for multi-devices testing of mobile-web hybrid apps. React Speed Coding implements Browsersync + Webpack + Hot Reloading. So if you make any changes in your JSX, these should update on all devices on saving the changes. While maintaining your current UI state. Isn’t this awesome!
GitUp (Trial). Graphical tool complementing Git workflow. We are find this tool useful for going back in time and revising commit logs for instance.
Webpack (Trial). We are implementing your React developer workflow using Webpack. Two chapters are dedicated to get you started with Webpack and help you production optimize the workflow.
Serverless Architecture (Assess). We are implementing serverless architecture using Firebase. Another technology worth evaluating is AWS Lambda, though it may not be in scope for this book.
Measuring speed
So it will be nice to define some baseline measurements of speed and see if we can improve these as we go through the book.
Website Performance. Google PageSpeed defines 25+ criteria for website performance as relative measures or percentile scores compared with rest of the Web. For example Enable Gzip Compression is 88% as recommended baseline.
As on May 9, 2016 the ReactSpeed.com website is evaluating grade A (93% average) on PageSpeed score, grade B (82% average) on YSlow score, 2.1s page load time, 834KB total page size, with 26 requests. View GTMetrix ReactSpeed.com report here.
As on Aug 9, 2016 while the React Speed app has more than 3,000 lines of code, we improve our page load time to 1.3s, 438KB page size, and only 13 requests back to the servers. Our page speed score improves to 95%, and YSlow score is 86%.
Load Impact (Radar Trial). Online load testing tool. We are using this tool to perform concurrent user load tests on ReactSpeed.com website.
As on May 9, 2016 with 20+ custom React components live on ReactSpeed website, we are recording faster than 200ms load time for our website for 25 concurrent users. That translates to handling approximately 2,50,000 monthly visitors. Excellent! View results snapshot here.
Build and Deploy Time. How long does it take to run the developer workflow.
As on May 9, 2016 our development server continuously builds and updates our app as we save our working code. Production build takes 5.3s with around 250 hidden modules. We deploy 44 files to Firebase several times during a day.
Time to Release. How long does it take to ship new features to production.
Since start of ReactSpeed project we have closed 150 production commits to GitHub over a 30 day period. Our peak is 40 commits during week of April 10.
Production Payload. How optimized are our production assets.
As on May 9, 2016 our CSS library is 4.7KB Gzip, 21KB minified with 25+ style modules. App JS bundle is 42KB minified. Vendor JS bundle is 192KB minified. HTML is 3KB.
Time to fix issues. How long does it take to fix issues in code. Code issues can be of several types including compliance with coding guidelines and best practices, logical bugs, usability issues, performance issues, among others.
As on May 10, 2016 it took us 6 hours to resolve 300+ issues down to 3 open issues using ESLint integration with Atom editor and Webpack. The issues ranged from coding best practices to refactoring requirements as per React coding patterns.
Continuos production build workflow. This can be measured by number of commands or developer actions required to complete one production ready build. Alternatively how automated is this lifecycle.
NPM for all the things. Can be measured based on number of project dependencies that are updated from NPM or popular managed repositories and CDNs. This is Trial stage at ThoughtWorks Technology Radar.
Static code analytics. This can be measured for number of lint warnings or errors. Complexity analysis of JavaScript code can be included apart from other static code analytics.
Why learn React comparing with Angular
One of the most important decisions modern app developers make is choosing the right front-end framework for their technology stack. Most popular question relates to choosing React over Angular 2.
We recognize that React is at its core a simpler library representing the View pattern, while Angular 2 is a complete framework offering Model, View, and Controller architectural patterns.
React is actually an ecosystem of well designed and highly popular libraries, open sourced mostly by Facebook (React, React Native, Immutable, Flow, Relay, GraphQL), other leading developers (Redux, React Material UI, React Router), and industry leaders (Flipboard React Canvas, Airbnb Enzyme).
React + Redux for instance offer the Model (Store), View (React, Actions), and Controller (Reducers) pattern to compare on equal grounds with the Angular 2 stack.
Why learn Angular 2? It is like learning Yoga, from one Guru, in a large group.
If you are in a large team, Angular will be your choice to get everyone on the same page, faster, at scale.
Contrary to popular opinion on the subject, we think Angular 2 is faster to learn when compared to React for the same goals, simply because you are making fewer “first-time-learner or developer” decisions along your journey.
- Angular2 and TypeScript are opinionated,
- Most documentation is “single version of truth” from one source (Google, the authors of Angular and Microsoft, the authors of TypeScript),
- There is mostly “one Angular/TypeScript way” of doing things, so fewer decisions to make along your learning and development journey,
- Angular 2 API and TypeScript language are well documented.
- Official samples are up to date with latest changes in the API, well mostly.
- Development boilerplates or starters are fairly mature, some like Angular Universal are backed by Google/Angular core team.
- The development and build tool-chain is mostly addressed by Angular/TypeScript, and few popular starter projects.
Why learn React? It is like doing cross-training, with multiple experts, at multiple locations.
If you are in a lean team or a single developer-designer-architect, “the React way” may be more fun. Learning React is more rewarding in the long run. As you are making “hopefully informed” decisions all along your learning and development journey, you become a more thorough developer, designer, architect in the long haul. If you make your decisions by evaluating pros-cons of architectural and design patterns, you are becoming a better developer.
React is opinionated for fewer core concepts like one-way-data-binding and offers sensible workarounds even for that.
- There are many ways to develop in React starting from how to define React components, how to create React build pipeline, which frameworks to integrate with, how to wire up a backend, the list goes on.
- You will learn from multiple sources and authors, not just Facebook/Instagram, the authors of React. Having these multiple perspectives will give you stronger real-world decision making muscles!
- Facebook and the React community is very driven by app performance patterns. Most core React concepts are centered around creating high performance code.
- The React community is more component driven. You will most likely find more reusable code.
- The community is also increasingly driven by “Developer Experience”. Writing beautiful code, writing more manageable code, writing readable code, and tools that make developer’s experience more fun and visual. See kadirahq/react-storybook as an example.
In our experience learning both and going back and forth helps. Programming design patterns remain the same. Syntactical sugar changes. Learning one, reinforces the other.
Shared learning path between Angular 2 and React
JavaScript. JavaScript (ES5 and ES6) is fundamental. TypeScript transpiles to JavaScript. React-JSX-Babel tooling transpiles to JavaScript.
CSS3. You cannot do serious front-end coding without it.
HTML5. It is obvious, but extend your knowledge on concepts like Offline Storage and Device Access, best practice starters like HTML5 boilerplate.
Webpack. Modern day packaging, module bundling, build pipeline automation tooling.
Design Patterns and Object Oriented principles. Composition, Inheritance, Singletons, Pure Functions, Immutability, and many others are core concepts helping you in doing good development in general.
Algorithms and data structures. Serious development cannot be done without using these in a good measure.
Backend as a Service. Firebase, AWS Lamba, among others.
Microservices and REST/APIs. No modern app is built in isolation these days.
So, here is a learning path if you want to go beyond React. Learn React first, build some reusable components, learn the component design workflow. Learn Angular 2 next, try reusing your component design and above mentioned shared learning here. Maybe round off your knowledge by learning Meteor (more opinionated with best practice patterns for speed coding and performance) and integrating React and Angular, replacing Meteor’s Blaze.
Setup React Webpack
You will learn in this chapter how to setup React development environment starting from scratch. By the end of this chapter we will have a starter boilerplate to develop React apps.
We will cover following topics in this chapter.
- How to install Node.js and use Node Version Manager
- Setup package.json to manage your NPM dependencies
- Quick access companion code for this book using Github
- Install starter dependencies for React, Webpack, and Babel
- Create Webpack configuration for development pipeline automation
- Write a simple React app to run your Webpack setup
Code Along. You can clone the source for this entire book, change to app directory, checkout just the code for this chapter, install and start the app to launch the local version in your default browser.
Preview complete demo website hosted on Firebase, as you code this app by the end of this book.
View current chapter demo of the app we build in this chapter.
Installing Node.js
You will need Node.js to get started with React. Your Mac OS comes with Node pre-installed. However you may want to use the latest stable release.
Check you node release using node -v command.
We recommend installing or upgrading Node using Node Version Manager (NVM). Their Github repo documents install and usage.
To install NVM:
Now you can install a Node release by choosing one from Node releases page.
The command nvm install 5.10.1 installs a stable release for us.
One of the advantages of using NVM is you can switch between multiple node releases you may have on your system.
Here’s what our terminal looks like when using nvm ls to list installed node releases.
Using nvm use x.y.z command we can switch to x.y.z installed node release.
Setting up package.json
You will require package.json to manage your NPM dependencies and scripts.
Create a new one using npm init command, selecting defaults where uncertain.
This is what our package.json looks like as we start off. Note that we added
the private flag to avoid accidental publishing of the project to NPM repo,
and also to stop any warnings for missing flags like project repo.
{
"name": "react-speed-book",
"version": "1.0.0",
"description": "Companion code for React Speed Coding book",
"main": "index.js",
"private": true,
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"repository": {
"type": "git",
"url": "git+https://github.com/manavsehgal/react-speed-book.git"
},
"author": "Manav Sehgal",
"license": "MIT",
"bugs": {
"url": "https://github.com/manavsehgal/react-speed-book/issues"
},
"homepage": "https://github.com/manavsehgal/react-speed-book#readme"
}
The dependencies section will start showing up as we add npm dependencies.
Installing starter dependencies
Before we start writing our React app we need to install starter dependencies for our development environment. React uses JSX as the XML-like syntax extension over JavaScript to specify component tree structure, data flow, and event handlers. JSX is processed by Webpack module bundler using specific loaders or convertors.
React recommends JavaScript ES6 for latest features and best practices. ES6 needs Babel for compiling to ES5 and maintain browser compatibility. Babel integrates with Webpack to stitch it all together for our app.
React and React DOM
React is available via NPM and this is the recommended way of using React in a project.
React core is available in the react package. The react-dom package targets
browser DOM for rendering React. React enables several targets including iOS, Android
for rendering React apps.
Webpack
Webpack is used for module packaging, development, and production pipeline automation.
We will use webpack-dev-server during development and webpack to create production
builds.
HTML generation
You can add functionality to Webpack using plugins. We will use automatic HTML
generation plugins for creating index.html for our app.
The html-webpack-plugin webpack plugin will refer to template configured
within webpack configuration to generate our index.html file.
Loaders
Webpack requires loaders to process specific file types. CSS loader
resolves @import interpreting these as require() statements.
Style loader turns CSS into JS modules that inject <style> tags. JSON
loader enables us to import local JSON files when using data fixtures
during prototyping our app.
PostCSS and Normalize CSS
PostCSS loader adds CSS post-processing capabilities to our app. This includes
Sass like capabilities including CSS variables and mixins using precss and
automatic vendor prefixes using the autoprefixer plugin for PostCSS.
Normalize CSS offers sensible resets for most use cases. Most CSS frameworks include it.
The postcss-easy-import plugin enables processing @import statements
with rules defined in webpack configuration.
Babel
Babel compiles React JSX and ES6 to ES5 JavaScript. We need babel-loader
as Webpack Babel loader for JSX file types.
Hot loading using babel-preset-react-hmre makes
your browser update automatically when there are changes to code,
without losing current state of your app.
ES6 support requires babel-preset-es2015 Babel preset.
Configure Babel .babelrc
Babel configuration is specified in .babelrc file. React Hot Loading is
required only during development.
{
"presets": ["react", "es2015"],
"env": {
"development": {
"presets": ["react-hmre"]
}
}
}
Dependencies in package.json
The dependencies within package.json now lists all the installed dependencies for our app so far.
"dependencies": {
"react": "^15.3.0",
"react-dom": "^15.3.0"
},
"devDependencies": {
"autoprefixer": "^6.4.0",
"babel-core": "^6.13.2",
"babel-loader": "^6.2.4",
"babel-preset-es2015": "^6.13.2",
"babel-preset-react": "^6.11.1",
"babel-preset-react-hmre": "^1.1.1",
"copy-webpack-plugin": "^3.0.1",
"css-loader": "^0.23.1",
"html-webpack-plugin": "^2.22.0",
"json-loader": "^0.5.4",
"normalize.css": "^4.2.0",
"postcss-easy-import": "^1.0.1",
"postcss-loader": "^0.9.1",
"precss": "^1.4.0",
"style-loader": "^0.13.1",
"webpack": "^1.13.1",
"webpack-dev-server": "^1.14.1"
}
Configure Webpack in webpack.config.js
Webpack configuration drives your development pipeline, so this is a really important file to understand. We will split various sections of the config file to aid step-by-step learning.
Initialization
To start off, you need to initialize the config file with dependencies. These include webpack itself, an HTML generation plugin, a webpack plugin to copy folders from development to build target, and Node path library for initializing default paths.
Next we initialize the default paths. We also configure defaults for our HOST and PORT configuration.
// Initialization
const webpack = require('webpack');
// File ops
const HtmlWebpackPlugin = require('html-webpack-plugin');
// Folder ops
const CopyWebpackPlugin = require('copy-webpack-plugin');
const path = require('path');
// PostCSS support
const postcssImport = require('postcss-easy-import');
const precss = require('precss');
const autoprefixer = require('autoprefixer');
// Constants
const APP = path.join(__dirname, 'app');
const BUILD = path.join(__dirname, 'build');
const STYLE = path.join(__dirname, 'app/style.css');
const PUBLIC = path.join(__dirname, 'app/public');
const TEMPLATE = path.join(__dirname, 'app/templates/index.html');
const NODE_MODULES = path.join(__dirname, 'node_modules');
const HOST = process.env.HOST || 'localhost';
const PORT = process.env.PORT || 8080;
- APP path is used to specify the app entry point, location of the root component
- BUILD path specifies the target folder where production compiled app files will be pushed
- STYLES path indicates the root CSS file that imports other styles
- PUBLIC path is a folder in development that is copied as-is to root of BUILD, used for storing web server root files like robots.txt and favicon.ico, among others
- TEMPLATE specifies the template used by html-webpack-plugin to generate the index.html file
- NODE_MODULES path is required when including assets directly from installed NPM packages
Entry points and extensions
Next section defines your app entry, build output, and the extensions which will resolve automatically.
module.exports = {
// Paths and extensions
entry: {
app: APP,
style: STYLE
},
output: {
path: BUILD,
filename: '[name].js'
},
resolve: {
extensions: ['', '.js', '.jsx', '.css']
},
Loaders
We follow this by defining the loaders for processing various file types used within our app.
React components will use .jsx extension. The React
JSX and ES6 is compiled by Babel to ES5 using the babel webpack loader.
We use the cacheDirectory parameter to improve repeat development compilation time.
The include key-value pair indicates where webpack will look for these files.
CSS processing is piped among style for injecting CSS style tag, css for
processing import paths, and postcss for using various plugins on the CSS itself.
We need JSON processing much later in the book to enable loading of local JSON files storing data fixtures (sample data) for our app.
module: {
loaders: [
{
test: /\.jsx?$/,
loaders: ['babel?cacheDirectory'],
include: APP
},
{
test: /\.css$/,
loaders: ['style', 'css', 'postcss'],
include: [APP, NODE_MODULES]
},
{
test: /\.json$/,
loader: 'json',
include: [APP, NODE_MODULES]
}
]
},
PostCSS plugins configuration
PostCSS requires further configuration to handle how PostCSS plugins behave.
Now we add postcssImport which enables Webpack build to process @import
even from node_modules directory directly.
Sequence matters as this is the order of execution for the PostCSS plugins. Process imports > compile Sass like features to CSS > add vendor prefixes.
// Configure PostCSS plugins
postcss: function processPostcss(webpack) { // eslint-disable-line no\
-shadow
return [
postcssImport({
addDependencyTo: webpack
}),
precss,
autoprefixer({ browsers: ['last 2 versions'] })
];
},
Configure webpack-dev-server
Now that we have loaders configured, let us add settings for our development server.
Source maps are used for debugging information.
The devServer settings are picked up by webpack-dev-server as it runs.
The historyApiFallback enables local browser to be able to handle direct access
to route URLs in single page apps.
The hot flag enables hot reloading. Using the inline flag a small
webpack-dev-server client entry is added to the bundle which refresh the page on change.
The progress and stats flags indicate how webpack reports compilation progress
and errors.
// Source maps used for debugging information
devtool: 'eval-source-map',
// webpack-dev-server configuration
devServer: {
historyApiFallback: true,
hot: true,
progress: true,
stats: 'errors-only',
host: HOST,
port: PORT,
// CopyWebpackPlugin: This is required for webpack-dev-server.
// The path should be an absolute path to your build destination.
outputPath: BUILD
},
Plugins
We now wrap up by adding plugins needed during our development.
This section specifies the compilation workflow. First we use the DefinePlugin to
define the NODE_ENV variable.
We then activate the Hot Reloading plugin to refresh browser with any app changes.
Then we generate any HTML as configured in the HtmlWebpackPlugin plugin.
plugins: [
// Required to inject NODE_ENV within React app.
new webpack.DefinePlugin({
'process.env': {
'NODE_ENV': JSON.stringify('development') // eslint-disable-line\
quote-props
}
}),
new webpack.HotModuleReplacementPlugin(),
new CopyWebpackPlugin([
{ from: PUBLIC, to: BUILD }
],
{
ignore: [
// Doesn't copy Mac storage system files
'.DS_Store'
]
}
),
new HtmlWebpackPlugin({
template: TEMPLATE,
// JS placed at the bottom of the body element
inject: 'body'
})
]};
HTML webpack template for index.html
We can now add a custom template to generate index.html using the HtmlWebpackPlugin plugin.
This enables us to add viewport tag to support mobile responsive scaling of our app.
We also add icons for mobile devices. Following best practices from HTML5 Boilerplate,
we add html5shiv to handle IE9 and upgrade warning for IE8 users.
<!DOCTYPE html>
<html class="no-js" lang="">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>React Speed Coding</title>
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1\
">
<link rel="icon" href="/favicon.ico" />
<!--[if lt IE 9]>
<script src="//html5shiv.googlecode.com/svn/trunk/html5.js"></\
script>
<script>window.html5 || document.write('<script src="js/html5s\
hiv.js"><\/script>')</script>
<![endif]-->
</head>
<body>
<!--[if lt IE 8]>
<p class="browserupgrade">You are using an <strong>outdated</s\
trong> browser. Please <a href="http://browsehappy.com/">upgrade your \
browser</a> to improve your experience.</p>
<![endif]-->
<div id="app"></div>
<!-- Google Analytics: change UA-XXXXX-X to be your site's ID. -->
</body>
</html>
Configuring startup scripts in package.json
We can configure startup scripts in package.json to speed up our development even further.
Before we do that, let us create a copy of webpack.config.js as webpack.prod.config.js intended
for production build version of our webpack configuration. We will only make one change in the
production configuration. Changing NODE_ENV in plugins section from development to production value.
Now npm start will run webpack-dev-server using inline mode which works well with hot reloading
browser when app changes without manually refreshing the browser.
Running npm run build will use webpack to create our production compiled build.
"scripts": {
"start": "NODE_ENV=development webpack-dev-server --inline",
"build": "NODE_ENV=production webpack --config webpack.prod.config.j\
s"
},
The webpack-dev-server will pick up the webpack.config.js file configuration by default.
Run webpack setup
index.js
Add index.js in the root of our development folder.
import React from 'react';
import ReactDOM from 'react-dom';
ReactDOM.render(
<h1>App running in {process.env.NODE_ENV} mode</h1>,
document.getElementById('app')
);
We will learn each aspect of a React component in the next chapter. For right now we are writing a minimal React app to test our Webpack configuration.
style.css
We also import the Normalize CSS library in our main style entry file.
@import 'normalize.css';
public/ folder
To test how are public folder is copied over to build, let us add favicon.ico file
to public folder in root of our development folder.
Running webpack
We can now run the development server using npm start command in the Terminal.
Now open your browser to localhost URL that your webpack dev server
suggests.
The browser app displays message that you are running in development mode. Try changing the message text and hit save. Your browser will refresh automatically.
You can also build your app to serve it using any web server.
First add a file server like so.
Now build and serve.
As you open your localhost URL with port suggested by the file server, you will note that the message now displays that you are running in production mode.
The build folder lists following files created in our webpack build.
Congratulations… You just built one of the most modern development environments on the planet!
ES6 React Guide
This chapter guides you through important React concepts and ES6 features for speeding up your React learning and development journey.
You will learn following concepts in this chapter.
- How to define a React component using ES6 syntax
- What are modules and how to import and export React components
- Why we need constructors
- How components talk to each other and the UI using events, props, and state
- Importance of stateless components
- Using React Chrome Extension to inspect your component hierarchy at runtime
For Speed Coding in React, ES6 is essential. Not only does it reduce the amount of code you end up writing, ES6 also introduces language patterns for making your app better designed, more stable, and performant.
Let us create a Hello World app to understand the React and ES6 features together. Subsequent chapters introduce more React and ES6 features based on the context of samples written for the chapter. This spreads your learning journey as you apply these concepts.
Code Along. You can clone the source for this entire book, change to app directory, checkout just the code for this chapter, install and start the app to launch the local version in your default browser.
Preview complete demo website hosted on Firebase, as you code this app by the end of this book.
View current chapter demo of the app we build in this chapter.
Hello World React
We will write a Hello World app with three custom components. A component to contain our app, a Hello component to render the greeting message, and a World component to handle user events like changing greeting or adding a name.
Component composition and naming
React apps follow component based development. So understanding how components are composed, how they relate to each other, simplifies several aspects of your React learning path. This includes understanding how React app folders and files are organized.
Component Hierarchy. React has owner components which render or set properties on other components. This ownership continues across all components building a tree-like hierarchy.
Root Component. In case of our Hello World ap, index.jsx represents
the root component (one that does not have an owner).
The root component owns and renders World component.
The World component is owner of Hello component.
Component File Naming. Root component inside a folder is named index.jsx and
the component name takes on the name of the folder, app in this case.
Components other than root are named same as the component class names, including PascalCase.
Refer naming conventions in Airbnb style guide.
Files and folder structure
This is the files and folder hierarchy you will create by the end of this chapter.
Root component index.jsx
We start by writing the entry point to our HelloWorld React app.
We replace the index.js created in the last chapter with a new one we
start from scratch.
Module import
In React each component is typically defined in a single file, also known as a module.
Any dependencies are imported using import statement.
The statement specifies name of the exported
component, constant, or function from the dependencies.
Dependencies are then used within a component. Dependencies are also used as rendered components
within an owner component. Like in our case World component is imported
by app root component before it is rendered.
import React from 'react';
import ReactDOM from 'react-dom';
import World from './components/World.jsx';
ReactDOM.render(
<World />,
document.getElementById('app')
);
Thinking in modules is central to how Webpack bundles your code and traces dependencies while creating chunks. However, Webpack 1.x does not natively support ES6 modules, though this is on their 2.x roadmap. This is where Babel steps in. Read more about Webpack ES6 support on the Webpack official docs.
The ReactDOM.render method uses React library targeting DOM output to identify
a DOM element id as target for rendering our entire app component hierarchy,
starting with the World component.
World.jsx component
Now we write the World component which renders the Hello component
with a message and handles user inputs.
Class definition
We start by importing Hello component which we will render in World component.
A module exports a component using export default keywords. There can only
be one such export. While importing such components we do not need to use
the { } braces.
All React components extend React.Component. This enables our components to have access to React lifecycle methods and other features.
import React from 'react';
import Hello from './Hello.jsx';
export default class World extends React.Component {
Constructor
The constructor of our World component highlights three most important
features of how components talk to each other and the user.
State. Changing UI or internal state of a component is maintained using this.state
object. When state changes, rendered markup is updated by re-invoking the render() method.
Props. Properties are the mechanism to pass data from owner to rendered components.
Events. Methods or event handlers are bound to UI events (like onClick) to perform actions when the event takes place.
Constructor is called when component is created, so it is the right place for the following three objectives.
- Using
super(props)keyword to make thepropsobject available to React.Component methods. - Setting initial component state. Using
this.stateobject. One can set state to default values or properties passed from owner component accessingpropsobject. - Binding event handlers to
thiscontext of the component class. Usingbind(this)method.
constructor(props) {
super(props);
this.state = {
currentGreeting: props.greet,
value: 'ReactSpeed'
};
this.slangGreet = this.slangGreet.bind(this);
this.hindiGreet = this.hindiGreet.bind(this);
this.handleNameChange = this.handleNameChange.bind(this);
}
Event Handlers and setState
Components can exist with no events defined. In our HelloWorld app we define three events.
The slangGreet event handles user click on Slang link to change the greeting message accordingly. Likewise the hindiGreet does so with the Hindi greeting message.
The handleNameChange method handles user input in the input text box to change
the name of greeting sender in the message. The value state is available
to React controlled components as explained few sections later in this chapter.
We use setState method to change state within React components. This in turn
re-renders the component UI calling the render method.
slangGreet() {
this.setState({ currentGreeting: 'Yo!' });
}
hindiGreet() {
this.setState({ currentGreeting: 'Namaste' });
}
handleNameChange(event) {
this.setState({ value: event.target.value });
}
JSX and the render method
Let us now write the render method for World component. React component is
rendered using JSX syntax. JSX is HTML-like syntax where the nodes are
actually native React components providing same functionality as the
HTML DOM equivalents. So <div>, <h2>, <a>, and others used in the JSX
code are all native React components.
render() {
const renderGreeting = this.state.value
? `${this.state.value} says ${this.state.currentGreeting}`
: this.state.currentGreeting;
return (
<div className="World-card">
<Hello greet={renderGreeting} message="World!" />
<h2>
<a onClick={this.slangGreet}>Slang</a>
OR
<a onClick={this.hindiGreet}>Hindi</a>
</h2>
<input
type="text" value={this.state.value}
placeholder="Enter a name"
onChange={this.handleNameChange}
/>
</div>
);
}}
In the next four sections we will break down the render method JSX to understand more ES6 React concepts.
Template literals and ternary conditionals
We are using ES6 template literals as strings with back-ticks. Template
literals allow embedded expressions using the ${expression} syntax.
We are also using the JavaScript ternary conditional expression to set
the JSX value of renderGreeting based on value state.
const renderGreeting = this.state.value
? `${this.state.value} says ${this.state.currentGreeting}`
: this.state.currentGreeting;
Properties
Properties are used for passing input data from Root/Owner component to Child. Owner defines a property=value which is used within rendered component. The “Owner-ownee” relationship can exist without property passing, as in owner simply rendering a component.
<Hello greet={renderGreeting} message="World!" />
Event UI binding
Event UI binding is done by passing a prop named after the event onClick in
this case and the bound event handler method.
<a onClick={this.slangGreet}>Slang</a>
OR
<a onClick={this.hindiGreet}>Hindi</a>
Controlled components
Current UI state changes as user clicks
on greeting language links. We are also processing input data
using this.state.value provided by React. The input control used in this
example does not maintain its own state. It is known as Controlled Component as opposed to
Uncontrolled Component if the value property is not used. Uncontrolled components
manage their own state. Read more about handling forms at Facebook React documentation.
<input
type="text" value={this.state.value}
placeholder="Enter a name"
onChange={this.handleNameChange}
/>
PropTypes and defaultProps
At the end of the class definition we define default properties and property types on the component constructor.
The propTypes are used in property validation during development to throw warnings
in the Browser’s JavaScript console, if your code is not meeting the validation criteria.
Read more on Prop Validation in Facebook post that lists various types,
including custom validations.
World.propTypes = {
greet: React.PropTypes.string.isRequired
};
World.defaultProps = {
greet: 'Hello'
};
So if you change the value of greet to any number, the app will run, however you will see following warning in your browser console.
ES7 Property Initializers
Property initializers are an ES7 Stage 1 proposed feature.
In the prior section we were using class properties by
defining the World.propTypes and World.defaultProps outside
of the class definition on the component constructor.
Now using babel-plugin-transform-class-properties we can bring these
within the class definition.
Install the Babel plugin supporting this ES7 transform.
Update .babelrc with this new plugin.
{
"presets": ["react", "es2015"],
"env": {
"development": {
"presets": ["react-hmre"]
}
},
"plugins": ["transform-class-properties"]
}
Next we update our class definition like so.
export default class World extends React.Component {
static propTypes = {
greet: React.PropTypes.string.isRequired
}
static defaultProps = {
greet: 'Hello'
}
constructor(props) {
Note the use of static statement before initializing propTypes
and defaultProps in our class definition.
Complete World.jsx listing
We can further reduce few lines of code from our World component by
importing PropTypes and Component from React core.
Here is the complete World component listing.
import React, { PropTypes, Component} from 'react';
import Hello from './Hello.jsx';
export default class World extends Component {
static propTypes = {
greet: PropTypes.string.isRequired
}
static defaultProps = {
greet: 'Hello'
}
constructor(props) {
super(props);
this.state = {
currentGreeting: props.greet,
value: 'ReactSpeed'
};
this.slangGreet = this.slangGreet.bind(this);
this.hindiGreet = this.hindiGreet.bind(this);
this.handleNameChange = this.handleNameChange.bind(this);
}
slangGreet() {
this.setState({ currentGreeting: 'Yo!' });
}
hindiGreet() {
this.setState({ currentGreeting: 'Namaste' });
}
handleNameChange(event) {
this.setState({ value: event.target.value });
}
render() {
const renderGreeting = this.state.value
? `${this.state.value} says ${this.state.currentGreeting}`
: this.state.currentGreeting;
return (
<div className="World-card">
<Hello greet={renderGreeting} message="World!" />
<h2>
<a onClick={this.slangGreet}>Slang</a>
OR
<a onClick={this.hindiGreet}>Hindi</a>
</h2>
<input
type="text" value={this.state.value}
placeholder="Enter a name"
onChange={this.handleNameChange}
/>
</div>
);
}
}
Hello.jsx stateless component
The Hello component renders Hello World message based on how World
component calls it and current UI state.
Our Hello component is stateless. It does not define or change any state.
We are using arrow functions which are ES6 shorthand for writing functions.
import React from 'react';
const Hello = ({ greet, message }) => (
<h1>{greet} {message}</h1>
);
Hello.propTypes = {
greet: React.PropTypes.string.isRequired,
message: React.PropTypes.string.isRequired
};
export default Hello;
Component styles in world.css
We can add some styles to our app. The /app/styles/components/world.css path
is used to create style for our World component.
.World-card {
background: white;
border: 1px solid lightgrey;
border-radius: 3px;
box-shadow: 1px 1px 1px 0 darkgrey;
padding: 0.8em 1em;
width: 300px;
margin: 10px;
text-align: center;
}
Base styles in element.css
We also add some shared styles in /app/styles/base/element.css file.
html {
height: 100%;
color: black;
font-family: 'Open Sans', sans-serif;
font-size: 18px;
font-weight: 400;
}
h1 {
font-weight: 300;
font-size: 2em;
}
h2 {
font-size: 1.333em;
font-weight: 400;
}
a {
color: steelblue;
text-decoration: none;
}
a:focus,
a:hover {
border-bottom: 1px solid steelblue;
cursor: pointer;
}
Entry CSS using style.css
Finally we include our base and component styles, along with Normalize resets from the NPM module we installed earlier in this chapter.
@import 'normalize.css';
@import 'styles/base/elements';
@import 'styles/components/world';
The CSS entry file is stored at the /app/style.css path.
Run development server
This completes our first React app. Now run the app using the development server.
Once the app runs you should see following message from webpack-dev-server in your terminal window.
Browse to your app on the url mentioned in webpack output. Now try changing some code like the style background or the Hello World message and hit save. Your browser should update the app without refreshing state.
When this hot loading update happens you will see following output in the browser console.
Now we build and serve our HelloWorld app.
You will see a different webpack output on your terminal this time.
As you may have noticed the build is not highly optimized. The app.js file is
a huge ~2MB and css turned into JavaScript! In the chapter Production Optimize Webpack
we will discuss various techniques to optimize for a production environment.
React Chrome Extension
In case you want to inspect how your components pass properties and how they are organized at runtime, you can install React Chrome Extension.
You can then select the code responsible for component UI and see the rendered UI highlighted. The extension will also update properties as they are passed along if you turn on the trace feature.