[React] Public Class Fields with React Components

Public Class Fields allow you to add instance properties to the class definition with the assignment operator (=). In this lesson, we'll look at their use case for simplifying event callbacks and state initialization with a React component.

Handle function:

// Better
handleClick = () => {
    ...
}

// Not good
constructor() {
    super();
    this.handleClick = this.handleClick.bind(this);
}

handleClick() {
   ...  
}

Handle State:

// Better
state = {count: 0}

// Not good
constructor() {
    super();
    this.state = {count: 0};
}

Using puiblic field, we can actually remove 'constructor' because it is no longer necessary.

class App extends React.Component {
  state = {clicks: 6}

  handleClick = () => {
    this.setState(prevState => {
      return {clicks: prevState.clicks + 1}
    })
  }

  render() {
    return (
      <div>
        <div>
          Click Count: {this.state.clicks}
        </div>
        <button
          onClick={this.handleClick}
        >
          Click Me!
        </button>
      </div>
    )
  }
}

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