React/JSX Style Guide

A mostly reasonable approach to React and JSX, based on the Airbnb styleguide of the same name

Table of Contents

1. Basic Rules
2. Naming
3. Alignment
4. Quotes
5. Spacing
6. Props
7. Parentheses
8. Tags
9. Methods
10. Ordering

Basic Rules

• Only include one React component per file.
• Always use JSX syntax.
• Do not use React.createElement unless you're initializing the app from a file that is not JSX.

Class vs React.createClass

• Use class extends React.Component unless you have a very good reason to use mixins.

// bad
const Listing = React.createClass({
  render() {
    return <div />;
  }
});

// good
class Listing extends React.Component {
  render() {
    return <div />;
  }
}

Export at the end of the file

// bad
export default class Listing extends React.Component {
  ...
}

// good
class Listing extends React.Component {
  ...
}

export default Listing;

Naming

• Extensions: Use .js extension for React components.

• Filename: Use snake_case for filenames. E.g., reservation_card.js.

• Reference Naming: Use PascalCase for React components and camelCase for their instances:

  // bad
  const reservationCard = require('./reservation_card');
  
  // good
  const ReservationCard = require('./reservation_card');
  
  // bad
  const ReservationItem = <ReservationCard />;
  
  // good
  const reservationItem = <ReservationCard />;

  Component Naming: Use the filename as the component name. For example, reservation_card.js should have a reference name of ReservationCard. However, for root components of a directory, use index.js as the filename and use the directory name as the component name:

  // bad
  const Footer = require('./footer/footer.js')
  
  // bad
  const Footer = require('./footer/index.js')
  
  // good (note trailing slash)
  const Footer = require('./footer/')

Alignment

• Follow these alignment styles for JSX syntax

  // bad
  <Foo superLongParam="bar"
       anotherSuperLongParam="baz" />
  
  // good
  <Foo
    superLongParam        = "bar"
    anotherSuperLongParam = "baz"
  />
  
  // if props fit in one line then keep it on the same line
  <Foo bar="bar" />
  
  // children get indented normally
  <Foo
    superLongParam        = "bar"
    anotherSuperLongParam = "baz"
  >
    <Spazz />
  </Foo>

Quotes

• Always use double quotes (") for JSX attributes, but single quotes for all other JS.

  // bad
  <Foo bar='bar' />
  
  // good
  <Foo bar="bar" />
  
  // bad
  <Foo style={{ left: "20px" }} />
  
  // good
  <Foo style={{ left: '20px' }} />

Spacing

• Always include a single space in your self-closing tag.

  // bad
  <Foo/>
  
  // very bad
  <Foo                 />
  
  // bad
  <Foo
   />
  
  // good
  <Foo />

Props

• Always use camelCase for prop names.

  // bad
  <Foo
    UserName     = "hello"
    phone_number = {12345678}
  />
  
  // good
  <Foo
    userName    = "hello"
    phoneNumber = {12345678}
  />

Parentheses

• Wrap JSX tags in parentheses when they span more than one line:

  /// bad
  render() {
    return <MyComponent className="long body" foo="bar">
             <MyChild />
           </MyComponent>;
  }
  
  // good
  render() {
    return (
      <MyComponent className="long body" foo="bar">
        <MyChild />
      </MyComponent>
    );
  }
  
  // good, when single line
  render() {
    const body = <div>hello</div>;
    return <MyComponent>{body}</MyComponent>;
  }

Tags

• Always self-close tags that have no children.

  // bad
  <Foo className="stuff"></Foo>
  
  // good
  <Foo className="stuff" />

• If your component has multi-line properties, close its tag on a new line.

  // bad
  <Foo
    bar = "bar"
    baz = "baz" />
  
  // good
  <Foo
    bar = "bar"
    baz = "baz"
  />

Methods

• Do not use underscore prefix for internal methods of a React component.

  // bad
  React.createClass({
    _onClickSubmit() {
      // do stuff
    }
  
    // other stuff
  });
  
  // good
  class extends React.Component {
    onClickSubmit() {
      // do stuff
    }
  
    // other stuff
  });

Ordering

• Ordering for class extends React.Component:

1. constructor
2. optional static methods
3. getChildContext
4. componentWillMount
5. componentDidMount
6. componentWillReceiveProps
7. shouldComponentUpdate
8. componentWillUpdate
9. componentDidUpdate
10. componentWillUnmount
11. clickHandlers or eventHandlers like onClickSubmit() or onChangeDescription()
12. getter methods for render like getSelectReason() or getFooterContent()
13. Optional render methods like renderNavigation() or renderProfilePicture()
14. render

• How to define propTypes, defaultProps, contextTypes, etc...

import React, { Component, PropTypes } from 'react';

const { number, string } = PropTypes;

const propTypes = {
  id:   number.isRequired,
  url:  string.isRequired,
  text: string,
};

const defaultProps = {
  text: 'Hello World',
};

class Link extends Component {
  static methodsAreOk() {
    return true;
  }

  render() {
    return <a href={this.props.url} data-id={this.props.id}>{this.props.text}</a>
  }
}

Link.propTypes    = propTypes;
Link.defaultProps = defaultProps;

export default Link;

• Ordering for React.createClass:

1. propTypes
2. contextTypes
3. childContextTypes
4. mixins
5. statics
6. defaultProps
7. getDefaultProps
8. getInitialState
9. getChildContext
10. componentWillMount
11. componentDidMount
12. componentWillReceiveProps
13. shouldComponentUpdate
14. componentWillUpdate
15. componentDidUpdate
16. componentWillUnmount
17. clickHandlers or eventHandlers like onClickSubmit() or onChangeDescription()
18. getter methods for render like getSelectReason() or getFooterContent()
19. Optional render methods like renderNavigation() or renderProfilePicture()
20. render

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