🌈 React Cheat Sheet

A simple cheat sheet for facilitate the process in the workshops and event about React. Let me know if you see any problem, I'll love a pull request for improve this document.

Table of contents

• Installation
• No configuration
• ReactDOM
• Functional Stateless Component
• Class Component
• Composition
• Module component
• Hot Module Replacement
• Props
• State
• Methods and Events
• State manipulation
• Bindings
• Refs
• Keys
• Component Lifecycle
• Inline Styles
• React Router
• Storybook
• Tests
• a11y
• API comunication
• Flux
• Redux
• MobX
• Best Practices
• Concepts
  • Immutable
  • Functionnal programing
  • Virtual Dom
• ES6
  • Arrow Functions
    • Syntax
    • Advanced Syntax
  • Spread Operations
    • Spread in array literals
    • Spread in object literals

---

Installation

• Add the tags in your HTML

  <script src="https://unpkg.com/react@16/umd/react.development.js" crossorigin></script>
  <script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js" crossorigin></script>

• Run this scripts in your terminal

  $ npm install react react-dom
  

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No configuration

Just start with React no configuration (run the scripts bellow in your terminal)

• Install the React

  $ npm install -g create-react-app
  

• Create your application (change myApp to your application name)

  $ create-react-app myApp
  

• Go to the application folder and install the dependencies

  $ cd myApp
  $ npm install
  

• Start your application

  $ npm start
  

• Go to the browser by URL bellow and see your beautiful application
  • localhost:8080

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ReactDOM

import React, { Component } from 'react';
import ReactDOM from 'react-dom';

ReactDOM.render( <h1>Hello React Ladies</h1>, document.getElementById('root') );

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Functional Stateless Component

import React from 'react';

const Button = () =>
    <button> Apply</button>

export default Button;

import React from 'react';

const Button = ({ onClick, className = 'button', children  }) =>
    <button
        onClick={ onClick }
        className={ className }
        type='button'
    >
        { children }
    </button>

export default Button;

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Class Component

import React, { Component } from 'react';

class MyComponent extends Component {
    render() {
        return (
            <div className="main">
                <h1>Helo Devas</h1>
            </div>
        );
    }
}

export default MyComponent;

import React, { Component } from 'react';

class MyComponent () extends Compnent {
    constructor ( props ) {
    super(props);
    this.state = { message: 'Helo Devas' }
    };

    render() {
        return (
            <div className="main">
                <h1>{ this.state.message }</h1>
            </div>
        );
    }
}

export default MyComponent;

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Composition

import React, { Component } from 'react';
import ReactDOM from 'react-dom';

class Love extends Component {
    render() {
        return (
            <div clssName="love">
                <h1>My love</h1>
            </div>
        );
    }
}

class LoveList extends Component {
    render() {
        return (
            <div>
                <Love />
                <Love />
                <Love />
                <Love />
            </>
        );
    }
}

ReactDOM.render(
    <Love />,
    document.getElementById(´root´)
);

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Module component

//App.js
import React, { Component } from 'react';

class App extends Component {
    render() {
        return (
            <div className="app">
                <p>My App</p>
            </div>
        );
    }
}

export default App

//Index.js
import React, { Component } from 'react';
import ReactDOM from 'react-dom';
import App from './App.js';

class Index extends Component {
    render() {
        return (
            <div className="app">
                <App />
            </div>
        );
    }
}


ReactDOM.render (
    <Index />,
    document.getElementById('root')
);

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Hot Module Replacement

• Retain application state which is lost during a full reload.
• Save valuable development time by only updating what's changed.
• Tweak styling faster -- almost comparable to changing styles in the browser's debugger.

import React, { Component } from 'react';
import ReactDOM from 'react-dom';
import MyComponent from './MyComponent';

ReactDOM.render( <MyComponent />, document.getElementById('root') );

if (module.hot) {
    module.hot.accept();
}

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Props

import React, { Component } from 'react';

class App extends Component {
    render() {
        return (
            <div className="app">
                <p>My App {this.props.name}</p>
            </div>
        );
    }
}

class Index extends Component {
    render() {
        return (
            <div className="app">
                <App name="Simone"/>
            </div>
        );
    }
}

export default Index;

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State

import React, { Component } from 'react';

class App extends Component {
    constructor(props) {
        super(props);
        this.state = {messages: 0};
    } 

    render() {
        return (
            <div className="app">
                <p>My messages: {this.state.messages}</p>
            </div>
        );
    }
}

export default App;

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Methods and Events

import React, { Component } from 'react';

class App extends Component {

    escreve() {
      console.log("Eu te amo");
    }

    render() {
        return (
            <div className="app">
                <button onClick={this.escreve}>save</button>
            </div>
        );
    }
}

export default App;

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State manipulation

import React, { Component } from 'react';

class App extends Component {
    constructor() {
        super();
        this.state = { like: 0 };
    } 

    isLiked = () => {
      this.setState({ like: this.state.like + 1});
    }

    render() {
        return (
            <div className="app">
                <button onClick={ this.isLiked }>{ this.state.like }</button>
            </div>
        );
    }
}

export default App;

import React, { Component } from 'react';

class App extends Component {
    constructor() {
        super();
        this.state = { messages: ['JS', 'React'] };
    } 

    addMessages = () => {
        const updateMessages = [...this.state.messages, 'Polymer']
        this.setState({ messages: [...updateMessages] })
    }

    render() {
        return (
            <div className="app">
                <button onClick={this.addMessages}>add</button>
                {console.log(this.state.messages) /* ['JS', 'React', 'Polymer'] */}
            </div>
        );
    }
}

export default App;

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d

Bindings

import React, { Component } from 'react';

class MyComponent extends Component {
    constructor () {
    super();

    this.state = { list: list };

    this.doSomethingElse = this.doSomethingElse.bind(this);
    };

    doSomething = () => {
        // do something
        /* if don't have a parameter, you can use arrow function
           and don't need to use bind */
    }

    doSomethingElse ( itemId ) {
        // do something else
    }

    render() {
        return (
            <div className="main">
                {this.state.list.map( item =>
                ...
                    <button 
                        onClick={ this.doSomething } 
                        type="button"
                    >
                        Some Thing
                    </button>

                    <button 
                        onClick={ () => this.doSomethingElse( item.objectID ) } 
                        type="button"
                    >
                        Some Thing Else
                    </button>
                ...
                )}
            </div>
        );
    }
}

export default MyComponent;

---

ES6

Arrow Functions

Syntax

Basic syntax

```JS
( param1, param2, ..., paramN ) => { statements }

( param1, param2, ..., paramN ) =>  expression

( singleParam ) => { statements }

singleParam => { statements }

() => { statements }
```

Advanced Syntax

```JS
params => ({ foo: bar }) /* return an object literal expression */

( param1, param2, ...ladies ) =>  { statements } /* rest parameters */

( language = JS, ladies, ..., framework = React ) => { statements } /* default parameters */

const sum = ( [num1, num2] = [1, 2], { x: num3 } = { x : num1 + num2 } ) => num1 + num2 + num3  /*  destructuring within the parameter list */
sum() /* 6 */
```

---

Spread Operations

Spread in array literals

const basics = [ 'JS', 'HTML', 'CSS' ];
const frameworks = [ 'React', 'Vue' ];
const web = [ ...basics, ...frameworks ]; 
console.log(web); /* ['JS', 'HTML', 'CSS', 'React', 'Vue'] */

const addWeb = [ ...web, 'al11' ];
console.log(addWeb); /* ['JS', 'HTML', 'CSS', 'React', 'Vue', 'al11'] */

Spread in object literals

const basics = { behavior: 'JS', markup: 'HTML' };
const style = 'CSS';
const web = { ...basics, style }; 
console.log(web); /* { behavior: "JS", markup: "HTML", style: "CSS" } */

const devFront = { framework: 'react', event: 'React Conf' };
const devBack = { framework: 'django', state: 'cool' };

const cloneDev = { ...devFront };
console.log(cloneDev); /* { framework: 'react', event: 'React Conf' } */

const merged = { ...devFront, ...devBack };
console.log(cloneDev); /* { framework: 'django', event: 'React Conf', state: 'cool' } */