five ways for binding react methods

binding.js

// https://medium.freecodecamp.org/react-binding-patterns-5-approaches-for-handling-this-92c651b5af56
// Approach 1: Use React.createClass
var HelloWorld = React.createClass({
  getInitialState() {
    return { message: 'Hi' };
  },

  logMessage() {
    // this magically works because React.createClass autobinds.
    console.log(this.state.message);
  },

  render() {
    return (
      <input type="button" value="Log" onClick={this.logMessage} />
    );
  }
});

// Approach 2: Bind in Render
class HelloWorld extends React.Component {
  constructor(props) {
    super(props);
    this.state = { message: 'Hi' };
  }

  logMessage() {
    // This works because of the bind in render below.
    console.log(this.state.message);
  }

  render() {
    return (
      <input type="button" value="Log" onClick={this.logMessage.bind(this)} />
    );
  }
}

// Approach 3: Use Arrow Function in Render
class HelloWorld extends React.Component {
  constructor(props) {
    super(props);
    this.state = { message: 'Hi' };
  }

  logMessage() {
    // This works because of the arrow function in render below.
    console.log(this.state.message);
  }

  render() {
    return (
      <input type="button" value="Log" onClick={() => this.logMessage()} />
    );
  }
}

// Approach 4: Bind in Constructor
class HelloWorld extends React.Component {
  constructor(props) {
    super(props);
    this.state = { message: 'Hi' };
    this.logMessage = this.logMessage.bind(this);
  }

  logMessage() {
    // This works because of the bind in the constructor above.
    console.log(this.state.message);
  }

  render() {
    return (
      <input type="button" value="Log" onClick={this.logMessage} />
    );
  }
}

// Approach 5: Arrow Function in Class Property
class HelloWorld extends React.Component {
  // Note that state is a property,
  // so no constructor is needed in this case.
  state = {
    message: 'Hi'
  };

  logMessage = () => {
    // This works because arrow funcs adopt the this binding of the enclosing scope.
    console.log(this.state.message);
  };

  render() {
    return (
      <input type="button" value="Log" onClick={this.logMessage} />
    );
  }
}