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<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
<title>React Workshop</title>
<link rel="stylesheet" href="css/reveal.css">
<link rel="stylesheet" href="css/theme/black.css">
<link rel="stylesheet" href="css/app.css">
<!-- Theme used for syntax highlighting of code -->
<link rel="stylesheet" href="lib/css/zenburn.css">
<!-- Printing and PDF exports -->
<script>
var link = document.createElement( 'link' );
link.rel = 'stylesheet';
link.type = 'text/css';
link.href = window.location.search.match( /print-pdf/gi ) ? 'css/print/pdf.css' : 'css/print/paper.css';
document.getElementsByTagName( 'head' )[0].appendChild( link );
</script>
</head>
<body>
<div class="reveal">
<div class="slides">
<section data-markdown>
<script type="text/template">
# React In a Day
## Justin McCandless
<img alt="Dev Meetings Logo" src="./img/devmeetings_logo.png" width="500px" />
#### [justinmc.github.io/react-workshop](https://justinmc.github.io/react-workshop)
</script>#
<aside class="notes">
- Let Rithm School introduce themselves
</aside>
</section>
<section data-markdown>
<script type="text/template">
## Hi I'm Justin
<ul class="fragment">
<li>Engineer at Autodesk Life Sciences</li>
<li><3 React since 2015</li>
<li>@justinjmcc | justinmccandless.com</li>
</ul>
</script>
<aside class="notes">
- Gauge React experience in audience
</aside>
</section>
<section data-markdown>
<script type="text/template">
## What to Expect
<ul>
<li class="fragment">We're each going to build our own React app over the course of the day.</li>
<li class="fragment">We'll work in 5 separate "sprints" covering core React functionality.</li>
<li class="fragment">I'll present the sprint's topics while working through my app, then turn it over to you guys and help out in person.</li>
</ul>
<aside class="notes">
- Some discussion and you guys can show your work at the end of each sprint.
- How DevMeetings does things.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Quick Think of an App Idea
- That's what I'll be building ([full code on Github](https://github.com/justinmc/react-workshop-app)).
- Your app was intended to be something like a social network, but anything with a feed will work.</li>
<aside class="notes">
- If you have an idea you actually want to put in production some day, feel free to get started here!
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Outline for the day
- What is React?
- Sprint 0: Creating a static app
- Sprint 1: Dynamic state and props
- Lunch
- Sprint 2: Forms and mutating state
- Sprint 3: Asynchronous data (integrating an API)
- Sprint 4: Performance and Architecture
- References and how to keep learning
<aside class="notes">
- Hands on learning practical stuff, but also understand fundamentals.
</aside>
</script>
</section>
<section>
<section data-markdown>
<script type="text/template">
## What is React?
<aside class="notes">
- What this section is about:
- Understanding what React is, behind the curtain
- No magic
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## Roots: Static HTML
<br />
Source: [https://html5boilerplate.com/](https://html5boilerplate.com/)
<aside class="notes">
- History lesson </aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## Roots: Direct DOM Manipulation
Source: [http://codepen.io/justinmc/pen/oBRKeG](http://codepen.io/justinmc/pen/oBRKeG)
```javascript
<button class="adder">+1</button>
<div class="count">0</div>
```
```javascript
var adderEl = document.querySelector('.adder');
var countEl = document.querySelector('.count');
adderEl.addEventListener('click', function() {
var currentValue = countEl.innerHTML;
countEl.innerHTML = parseInt(currentValue) + 1;
});
```
<aside class="notes">
- I was originally going to call this slide "jQuery Spaghetti".
- This is great for simple interactivity, but is hard to maintain in large applications.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## Roots: MVC
<aside class="notes">
- Keep state in javascript, mutate state, and rerender.
- Backbone is a great example.
- Potential performance problems with totally rerendering too much.
- Potential architecture problem with needing to be wary of rerendering away temporary state
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## Enter React
<ol>
<li class="fragment">Render HTML based on data.</li>
<li class="fragment">Do subsequent renders incredibly quickly.</li>
<li class="fragment">That's pretty much it.</li>
</ol>
<aside class="notes">
- Very minimal.
- Not a full MVC setup.
- Plays well with others.
- Solves the performance problem of rerendering too much.
</aside>
</script>
</section>
<section data-markdown data-transition="none">
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## React: Data => HTML
```javascript
function MyReactComponent() {
const myButtonLabel = 'Click Me!';
const myButtonIsDisabled = false;
return (
<button
className="pretty-button"
disabled={myButtonIsDisabled}
>
{myButtonLabel}
</button>
);
}
```
<aside class="notes">
- This is JSX (coming up next).
</aside>
</script>
</section>
<section data-markdown data-transition="none">
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## React: Data => HTML
```javascript
function MyReactComponent() {
// Let's change this data
const myButtonLabel = 'Don\'t Click Me :(';
const myButtonIsDisabled = true;
return (
<button
className="pretty-button"
disabled={myButtonIsDisabled}
>
{myButtonLabel}
</button>
);
}
```
<aside class="notes">
- If the data changes, the output html changes to match it.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## Wait but how are you writing HTML in your JS?
<ul class="fragment">
<li>It's called JSX!</li>
<li>It's a preprocessing language that gets compiled to plain old javascript.</li>
</ul>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## JSX
```javascript
return (
<p className="prose">Lorem Ipsum</p>
);
```
=>
```javascript
return React.createElement(
"p",
{ className: "prose" },
"Lorem Ipsum"
);
```
If you want to play around with compiling to JSX, try [Babel's repl](https://babeljs.io/repl) (don't forget to turn on the "react" preset).
<aside class="notes">
- Very similar to document.createElement!
- We're going to use jsx in this workshop because it is very prevalent.
- But, take the time to convince yourself that there is no magic here.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## You said React was fast?
<ul>
<li class="fragment">React isn't just reinserting a whole new element each time something changes.</li>
<li class="fragment">It's doing DOM DIFFING!</li>
<li class="fragment">On a rerender, compares the current state of the DOM to the new state, then makes minimum number of operations needed to transition to the new state.</li>
</ul>
<aside class="notes">
- From what we've seen so far, you could imagine writing a library to insert these components into the dom yourself in a few hundred lines.
- There are some libraries that do this!
- Actually not bad performance in most cases.
- Think about how this solves the problem of rerendering a text input and having the cursor position change.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Introduction: What is React?</div>
## One more performance buzz word for you
<ul>
<li class="fragment">React doesn't actually look at the actual DOM to make it's comparison. It looks at the VIRTUAL DOM.</li>
<li class="fragment">The virtual DOM is React's own internal representation of the DOM designed to be super quick to inspect and make operations on.</li>
<li class="fragment">Why does React go through all this trouble to avoid working with the DOM? Because the DOM is a slow legacy dinosaur.</li>
</ul>
<aside class="notes">
- Not to be confused with the Shadow DOM.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Ok you guys pretty much know React now, let's build something.
<aside class="notes">
- Or at least I hope everyone understands what React is!
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
## Tips!
- Whenever you finish a task, commit!
- That way, if we have to move on while you're still working, you can stash and get back to a working state.
- Aim to finish green Basic tasks first, then polish up or pick and choose other tasks you want to try.
</script>
</section>
<section data-markdown>
<script type="text/template">
## [The Sprints](#/6)
</script>
</section>
</section>
<section>
<section data-markdown>
<script type="text/template">
## [Sprint 0](https://github.com/justinmc/react-workshop-app/tree/sprint0)
1. <span class="task-basic">Join chat: https://discord.gg/gpQ68nm</span>
1. <span class="task-basic">Generate a React app with [create-react-app](https://github.com/facebookincubator/create-react-app).</span>
1. <span class="task-basic">Initialize a git repository.
1. <span class="task-basic">Edit the big title on the page and see it update in your browser.</span>
1. <span class="task-basic">Create your own nested React component.</span>
1. <span class="task-basic">Make it awesome with CSS and static info.</span>
1. <span class="task-advanced">Install a linter like the [airbnb eslint config](https://www.npmjs.com/package/eslint-config-airbnb) and make your jsx code comply!</span>
1. <span class="task-extra">Install [redux](http://redux.js.org/), create a Container above your "Post" component, and feed it dummy data.</span>
<aside class="notes">
- Note that the title here links to the code in the github repo for this sprint.
- Write finish time on the board.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## create-react-app
- We're using it because it's easy and very widely used.
- It will be compiling our jsx, es7, and serving the compiled static assets.
- You can do fancier things with tools like Webpack and your own setup, though, so check those out if you end up with more build requirements.
<aside class="notes">
- We're using es7 for the same reason we're using jsx: it's very prevalent in the React community.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Default App.js component
<aside class="notes">
- This is what create-react-app generates for you.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Default App.js component
```javascript
import React, { Component } from 'react';
import logo from './logo.svg';
import './App.css';
class App extends Component {
render() {
return (
<div className="App">
<div className="App-header">
<img src={logo} className="App-logo" alt="logo" />
<h2>Welcome to React</h2>
</div>
<p className="App-intro">
To get started, edit <code>src/App.js</code> and save to reload.
</p>
</div>
);
}
}
export default App;
```
<aside class="notes">
- Note that we're using a class here instead of a function. Both are ok!
- Note the importing of css and an svg. create-react-app will make sure both get bundled where they need to.
- Note React must be imported into the page, even though it's never referenced (when compiled from JSX, it will use React!).
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Components as Classes and Functions
- The previous default component is equivalent to:
```javascript
function Component() {
return (
...
);
}
```
- The difference? Functions are purely functional, classes can be stateful (as we'll see).
<aside class="notes">
- Also, in a class it's possible to use React's built in lifecycle methods.
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Customize it
```
<div className="App-header">
<img src={logo} className="App-logo" alt="logo" />
<h2>Welcome to Justin's Awesome App!</h2>
</div>
```
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Customized it
```
return (
<div className="App">
<div
className="app-bar"
>
<div>Story Time</div>
</div>
<h2>Your Books</h2>
<ul>
<li>Treasure Island by Robert Louis Stevenson</li>
<li>Go Dog Go by Dr. Seuss</li>
</ul>
</div>
);
```
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Customized it
<aside class="notes">
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Components in Components
```
<ul>
<li>Treasure Island by Robert Louis Stevenson</li>
</ul>
```
<div class="fragment">
```
<ul>
<Book />
</ul>
```
</div>
<aside class="notes">
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Components in Components
`components/Book.js`
```
import React, { Component } from 'react';
class Book extends Component {
render() {
return (
<li>Treasure Island by Robert Louis Stevenson</li>
);
}
}
export default Book;
```
<aside class="notes">
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Components in Components
Back in `App.js`
```
import React, { Component } from 'react';
import Book from './components/Book';
import './css/App.css';
```
...
```
<ul>
<Book />
<Book />
<Book />
</ul>
```
<aside class="notes">
- Go Dog Go is gone, but that's a problem for next sprint!
</aside>
</script>
</section>
<section data-markdown>
<script type="text/template">
<div class="section">Sprint 0</div>
## Questions before we [get started](#/6)?
<aside class="notes">
</aside>
</script>
</section>
</section>
<section>
<section data-markdown>
<script type="text/template">
## [Sprint 1](https://github.com/justinmc/react-workshop-app/tree/sprint1)
1. <span class="task-basic">Feed your nested components data via props.</span>
1. <span class="task-basic">Add some local dynamic interactions with state.</span>
1. <span class="task-basic">Install the [React Dev Tools](https://chrome.google.com/webstore/detail/react-developer-tools/fmkadmapgofadopljbjfkapdkoienihi?hl=en) in your browser and use it to play with your props/state.</span>
1. <span class="task-advanced">Build some generic UI components for your app like a `<Button />`.</span>
1. <span class="task-extra">When the user performs an action like the one controlled by state in this sprint, call an action, dispatch an event, and modify state via a reducer.</span>
<aside class="notes">
- We'll get into more complicated dynamic stuff like text forms next sprint.
- Can do some really great frontend arch stuff by building generic reusable components!
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## Props and State
- Props is an object containing all data passed in to the component.
- State is an object representing all state internal to the component.
- Anytime either one changes, the component will attempt to rerender.
<aside class="notes">
- Component will kick off its whole process of DOM diffing and modifying the DOM if necessary.
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## Passing Props to the Book Component
`App.js`
```javascript
<ul>
<Book
title="Treasure Island"
author="Robert Louis Stevenson"
/>
<Book
title="Go Dog Go"
author="Dr. Seuss"
/>
</ul>
```
<aside class="notes">
- You can pass any javascript primitives or variables as props!
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## Passing Props to the Book Component
`Book.js`
```javascript
class Book extends Component {
render() {
return (
<li
className="book"
>
<div>
{this.props.title}
</div>
<div>
by {this.props.author}
</div>
</li>
);
}
}
```
<aside class="notes">
- What would this look like for a pure function component?
- (See next slide)
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## Passing Props to the Book Component (function)
`Book.js`
```javascript
function Book(props) {
return (
<li
className="book"
>
<div>
{props.title}
</div>
<div>
by {props.author}
</div>
</li>
);
}
```
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## Prop Types and Default Props
You can tell React what types to expect for each prop value, whether or not they're required, and what value to use as a default if not. There is a nice [list of all available prop types](https://facebook.github.io/react/docs/typechecking-with-proptypes.html) in the React docs.
```javascript
static defaultProps = {}
static propTypes = {
title: React.PropTypes.string.isRequired,
author: React.PropTypes.string.isRequired,
}
```
<aside class="notes">
- This syntax is equivalent to `Book.defaultProps = {};` etc.
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## State
I'll add a little "favorite" indicator on books that works like this:
<br />
<div class="section">Sprint 1</div>
<aside class="notes">
- Doesn't actually have any broader functionality, just toggles :)
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## State
`Book.js` and `Book.css`
```javascript
<div>
<span className="favorite" />
{this.props.title}
</div>
```
```css
.favorite {
display: inline-block;
background-color: #dfdfdf;
height: 16px;
width: 16px;
border-radius: 8px;
margin: 6px;
}
.favorite.enabled {
background-color: tomato;
}
```
<aside class="notes">
- What will this render?
- If I add the "enabled" class to the span, it will show filled red.
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## State
`Book.js`
```javascript
const favoriteClass = this.state.favorited ? 'enabled' : '';
return (
<li
className="book"
>
<div>
<span className={`favorite ${favoriteClass}`} />
{this.props.title}
</div>
```
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## Initial State
`Book.js`
```javascript
constructor(props) {
super(props);
this.state = {
favorited: false,
};
}
```
<aside class="notes">
- Previously was inheriting its constructor from React.Component.
- Must call super with props if you have a constructor.
- If you're not using es6 classes, you can use getInitialState.
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## Make it Dynamic
`Book.js`
```javascript
onClickFavorite = () => {
this.setState({
favorited: !this.state.favorited,
});
}
```
```
<span
className={`favorite ${favoriteClass}`}
onClick={this.onClickFavorite}
/>
```
<aside class="notes">
- `setState` will merge old state with new state and attempt a rerender.
- All supported events like `onClick`: https://facebook.github.io/react/docs/events.html#supported-events
- This is es7 class property declaration syntax.
- Otherwise, `onClickFavorite() {` and `this.onClickFavorite = this.onClickFavorite.bind(this)` in constructor.
- React doesn't want you to call `.bind` inside `render` for performance reasons.
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## State All Done
`Book.js`
```
import React, { Component } from 'react';
import '../css/Book.css';
class Book extends Component {
static propTypes = {
title: React.PropTypes.string.isRequired,
author: React.PropTypes.string.isRequired,
}
constructor(props) {
super(props);
this.state = {
favorited: false,
};
}
onClickFavorite = () => {
this.setState({
favorited: !this.state.favorited,
});
}
render() {
const favoriteClass = this.state.favorited ? 'enabled' : '';
return (
<li
className="book"
>
<div>
<span
className={`favorite ${favoriteClass}`}
onClick={this.onClickFavorite}
/>
{this.props.title}
</div>
<div>
{`by ${this.props.author}`}
</div>
</li>
);
}
}
export default Book;
```
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## Questions before we [get started](#/7)?
<aside class="notes">
- Text inputs will come next.
- Is there a `setProps`? No!
- Basically, props comes from state somewhere up the chain, so modify state and let it propagate.
- Can pass a function into child component to be called to modify parent state.
- We'll cover in more detail next sprint.
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## [Sprint 2](https://github.com/justinmc/react-workshop-app/tree/sprint2)
1. <span class="task-basic">Render an array of data by looping over it.</span>
1. <span class="task-basic">Build a controlled text input with state.</span>
1. <span class="task-advanced">Add validation to your form input.</span>
1. <span class="task-advanced">Add a few different types of form elements (radio buttons, checkboxes, dropdowns, etc.) and map their values to state.</span>
1. <span class="task-advanced">Try building an uncontrolled input.</span>
1. <span class="task-advanced">Play around with [refs](https://facebook.github.io/react/docs/refs-and-the-dom.html) for more direct DOM access.</span>
1. <span class="task-extra">Update your Flux/Redux store on form submission.</span>
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## Looping in JSX
- JSX is capable of rendering arrays of elements too!
- Just make sure each element has a unique `key` attribute.
<div class="fragment">
```javascript
<ul>
{
['a', 'b', 'c'].map((element) => (
<li key={element}>{element}</li>
))
}
</ul>
```
</div>
<div class="fragment">
</div>
<aside class="notes">
- React uses the `key` attribute to uniquely identify elements in order to do the most efficient DOM manipulations when your data changes.
- If you forget it in a loop, React will log a warning.
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## Looping in JSX
<ul>
<li>Why is `key` important?</li>
<li class="fragment">When rerendering, React uses `key` to determine how to reconcile the new and old array of elements:</li>
<ul>
<li class="fragment">If a key exists in the new elements and not in the old, add.</li>
<li class="fragment">If a key exists in the old elements and not in the new, remove.</li>
<li class="fragment">If a key exists in both, reconcile their differences.</li>
<li class="fragment">If a new element has no key, use its position</li>
</ul>
<li class="fragment">[Article on this topic](http://buildwithreact.com/article/in-depth-diffing)</li>
</ul>
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## Looping in JSX
- Using keys, the minimum DOM operation happens.
<aside class="notes">
- Only 1 li insertion
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## Looping in JSX
- Without using keys, not so efficient :(
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## Books from an array
- Get our books into `state` as an array.
```javascript
constructor(props) {
super(props);
this.state = {
books: [
{ title: 'Treasure Island', author: 'Robert Louis Stevenson' },
{ title: 'Go Dog Go', author: 'Dr. Seuss' },
],
};
}
```
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## Books from an array
- Render a `Book` component for each book in the array.
```
<ul>
{
this.state.books.map(book =>
<Book
key={book.title}
title={book.title}
author={book.author}
/>
)
}
</ul>
```
<aside class="notes">
- Now we're nicely set up to render any number of books.
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## Inputs
What does this render? (in a jsx React component)
```javascript
<input type="text" value="words go here" />
```
<div class="fragment">
</div>
<aside class="notes">
- And what happens if the user tries to change the input?
- Nothing! It won't change. React will rerender it immediately.
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## Inputs
What is the value of `event.target.value`?
```javascript
onChangeInput = (event) => {
console.log(event.target.value);
}
...
<input
type="text"
value="words go here"
onChange={this.onChangeInput}
/>
```
<div class="fragment">
Answer: The value that the user updated the input to (after first keystroke)
</div>
<aside class="notes">
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## [Controlled Inputs](https://facebook.github.io/react/docs/forms.html)
```javascript
constructor(props) {
super(props);
this.state = {
inputValue: 'words go here',
};
}
onChangeInput = (event) => {
this.setState({