react_redux

Coveo React/Redux - Cloud Platform Standards {

Other Standards

• TypeScript
• CSS & Sass

Table of Contents

1. Basic Rules
2. Class vs React.createClass vs stateless
3. Mixins
4. Naming
5. Declaration
6. Alignment
7. Quotes
8. Spacing
9. Props
10. Refs
11. Parentheses
12. Tags
13. Methods
14. Ordering
15. isMounted
16. Redux

Basic Rules

• Only include one React component per file.
  • However, multiple Stateless, or Pure, Components are allowed per file.
• Always use JSX/TSX syntax.
• Do not use React.createElement unless you're initializing the app from a file that is not JSX.

Class vs React.createClass vs stateless

• If you have internal state and/or refs, prefer class extends React.Component over React.createClass.

  // bad
  const Listing = React.createClass({
    // ...
    render(): JSX.Element {
      return <div>{this.state.hello}</div>;
    }
  });
  
  // good
  class Listing extends React.Component {
    // ...
    render(): JSX.Element {
      return <div>{this.state.hello}</div>;
    }
  }

  And if you don't have state or refs, use arrow functions over classes:

  // bad
  class Listing extends React.Component<Props, void> {
    render(): JSX.Element {
      return <div>{this.props.hello}</div>;
    }
  }
  
  // good
  const Listing = (props: Props) => (
    <div>{props.hello}</div>
  );

Mixins

• Do not use mixins.

Why? Mixins introduce implicit dependencies, cause name clashes, and cause snowballing complexity. Most use cases for mixins can be accomplished in better ways via components, higher-order components, or utility modules.

Naming

• Extensions: Use .tsx extension for React components.

• Filename: Use PascalCase for filenames. E.g., ReservationCard.tsx.

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

  // bad
  const ReservationItem = <ReservationCard />;
  
  // good
  const reservationItem = <ReservationCard />;

• Component Naming: Use the filename as the component name. For example, ReservationCard.tsx should have a reference name of ReservationCard.

  // bad
  import { Footer } from './Footer/index';
  
  // good
  import { Footer } from './Footer/Footer';

• Props Naming: Avoid using DOM component prop names for different purposes.

  Why? People expect props like style and className to mean one specific thing. Varying this API for a subset of your app makes the code less readable and less maintainable, and may cause bugs.

  // bad
  <MyComponent style="fancy" />
  
  // good
  <MyComponent variant="fancy" />

Declaration

• Do not use displayName for naming components. Instead, name the component by reference.

  // bad
  export React.createClass({
    displayName: 'ReservationCard',
    // stuff goes here
  });
  
  // good
  export class ReservationCard extends React.Component<Props, void> {
  }

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"
  >
    <Quux />
  </Foo>

Quotes

• Always use single quotes (') for JSX attributes, and all other JS.

  Why? Using the same quote style everywhere is more readable and less dangerous.

  // 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 />

• Do not pad JSX curly braces with spaces.

  // bad
  <Foo bar={ baz } />
  
  // good
  <Foo bar={baz} />

Props

• Always use camelCase for prop names.

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

• Omit the value of the prop when it is explicitly true.

  // bad
  <Foo
    hidden={true}
  />
  
  // good
  <Foo
    hidden
  />

• Always include an alt prop on <img> tags. If the image is presentational, alt can be an empty string or the <img> must have role='presentation'.

  // bad
  <img src='hello.jpg' />
  
  // good
  <img src='hello.jpg' alt='Me waving hello' />
  
  // good
  <img src='hello.jpg' alt='' />
  
  // good
  <img src='hello.jpg' role='presentation' />

• Do not use words like 'image', 'photo', or 'picture' in <img> alt props.

  Why? Screenreaders already announce img elements as images, so there is no need to include this information in the alt text.

  // bad
  <img src='hello.jpg' alt='Picture of me waving hello' />
  
  // good
  <img src='hello.jpg' alt='Me waving hello' />

• Use only valid, non-abstract ARIA roles.

  // bad - not an ARIA role
  <div role='datepicker' />
  
  // bad - abstract ARIA role
  <div role='range' />
  
  // good
  <div role='button' />

• Do not use accessKey on elements.

Why? Inconsistencies between keyboard shortcuts and keyboard commands used by people using screenreaders and keyboards complicate accessibility.

// bad
<div accessKey='h' />

// good
<div />

• Avoid using an array index as key prop, prefer a unique ID. (why?)

// bad
{todos.map((todo: Todo, index: number): JSX.Element =>
  <Todo
    {...todo}
    key={index}
  />
)}

// good
{todos.map((todo: Todo): JSX.Element => (
  <Todo
    {...todo}
    key={todo.id}
  />
))}

• Always define explicit defaultProps for all non-required props.

Why? propTypes are a form of documentation, and providing defaultProps means the reader of your code doesn’t have to assume as much. In addition, it can mean that your code can omit certain type checks.

Refs

• Always use ref callbacks.

  // bad
  <Foo
    ref='myRef'
  />
  
  // good
  <Foo
    ref={(ref) => { this.myRef = ref; }}
  />

Parentheses

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

  // bad
  render(): JSX.Element {
    return <MyComponent className='long body' foo='bar'>
             <MyChild />
           </MyComponent>;
  }
  
  // good
  render(): JSX.Element {
    return (
      <MyComponent className='long body' foo='bar'>
        <MyChild />
      </MyComponent>
    );
  }
  
  // good, when single line
  render(): JSX.Element {
    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

• Use arrow functions to close over local variables.

Why? It creates a new function on each render, which is desirable.

```typescript
const ItemList = (props: Props): JSX.Element => {
  return (
    <ul>
      {props.items.map((item, index) => (
        <Item
          key={item.key}
          onClick={() => doSomethingWith(item.name, index)}
        />
      ))}
    </ul>
  );
}
```

• Use arrow functions for the render method in the constructor.

  // bad
  class extends React.Component<Props, void> {
    private onClickDiv() {
      // do stuff
    }
  
    render(): JSX.Element {
      return <div onClick={this.onClickDiv} />;
    }
  }
  
  // good
  class extends React.Component<Props, void> {
    private onClickDiv() {
      // do stuff
    }
  
    render(): JSX.Element {
      return <div onClick={() => this.onClickDiv()} />;
    }
  }

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

  Why? Underscore prefixes are sometimes used as a convention in other languages to denote privacy. But, unlike those languages, TypeScript supports the private keyword to design an entity as private.

  // bad
  React.createClass({
    _onClickSubmit() {
      // do stuff
    },
  
    // other stuff
  });
  
  // good
  class extends React.Component<Props, void> {
    private onClickSubmit() {
      // do stuff
    }
  
    // other stuff
  }

• Be sure to return a value in your render methods.

  // bad
  render(): JSX.Element {
    (<div />);
  }
  
  // good
  render(): JSX.Element {
    return (<div />);
  }

Ordering

• Ordering for class extends React.Component:

1. optional static methods
2. constructor
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

• Ordering for React.createClass:

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

isMounted

• Do not use isMounted.

Why? isMounted is an anti-pattern, is not available when using ES6 classes, and is on its way to being officially deprecated.

Redux

• Seperate components from their actions and reducers. Thus, you should have one file for your actions, one for your reducers, and one for your component.

• The file name for your actions should be the name of the component + the suffix Actions.

• The file name for your reducers should be the name of the component + the suffix Reducers.

⬆ back to top

};