React component function call only updates one component instance

Pass event handlers and other functions as props to child components:

<button onClick={this.handleClick}>

Bind in Constructor (ES2015)

class Foo extends Component {
  constructor(props) {
    super(props);
    this.handleClick = this.handleClick.bind(this);
  }
  handleClick() {
    console.log('Click happened');
  }
  render() {
    return <button onClick={this.handleClick}>Click Me</button>;
  }
}

Class Properties (Stage 3 Proposal)

class Foo extends Component {
  // Note: this syntax is experimental and not standardized yet.
  handleClick = () => {
    console.log('Click happened');
  }
  render() {
    return <button onClick={this.handleClick}>Click Me</button>;
  }
}

Bind in Render

class Foo extends Component {
  handleClick() {
    console.log('Click happened');
  }
  render() {
    return <button onClick={this.handleClick.bind(this)}>Click Me</button>;
  }
}

Arrow Function in Render

class Foo extends Component {
  handleClick() {
    console.log('Click happened');
  }
  render() {
    return <button onClick={() => this.handleClick()}>Click Me</button>;
  }
}

In this traditional UI model, it is up to you to take care of creating and destroying child component instances. If a Form component wants to render a Button component, it needs to create its instance, and manually keep it up to date with any new information.

class Form extends TraditionalObjectOrientedView {
  render() {
    // Read some data passed to the view
    const { isSubmitted, buttonText } = this.attrs;

    if (!isSubmitted && !this.button) {
      // Form is not yet submitted. Create the button!
      this.button = new Button({
        children: buttonText,
        color: 'blue'
      });
      this.el.appendChild(this.button.el);
    }

    if (this.button) {
      // The button is visible. Update its text!
      this.button.attrs.children = buttonText;
      this.button.render();
    }

    if (isSubmitted && this.button) {
      // Form was submitted. Destroy the button!
      this.el.removeChild(this.button.el);
      this.button.destroy();
    }

    if (isSubmitted && !this.message) {
      // Form was submitted. Show the success message!
      this.message = new Message({ text: 'Success!' });
      this.el.appendChild(this.message.el);
    }
  }
}

When an element’s type is a string, it represents a DOM node with that tag name, and props correspond to its attributes. This is what React will render. For example:

{
  type: 'button',
  props: {
    className: 'button button-blue',
    children: {
      type: 'b',
      props: {
        children: 'OK!'
      }
    }
  }
}

This element is just a way to represent the following HTML as a plain object:

<button class='button button-blue'>
  
    OK!
  
</button>

However, the type of an element can also be a function or a class corresponding to a React component:

{
  type: Button,
  props: {
    color: 'blue',
    children: 'OK!'
  }
}

This feature lets you define a DangerButton component as a Button with a specific color property value without worrying about whether Button renders to a DOM <button>, a <div>, or something else entirely:

const DangerButton = ({ children }) => ({
  type: Button,
  props: {
    color: 'red',
    children: children
  }
});