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React - Components

React - Components

Components are reusable in react.js. You can inject value into props as given below :


function Welcome(props) {
  return <h1>Hello, {props.name}</h1>;
}

const element = <Welcome name="Faisal Arkan" />;
ReactDOM.render(
  element,
  document.getElementById('root')
);

The value name="Faisal Arkan" will be assigned to {props.name} from function Welcome(props) and returns a component <h1>Hello, Faisal Arkan</h1> which is saved into the const variable element. The component can then be rendered via ReactDOM.render(element, document.getElementById('root'));. document.getElementById('root') in this case is the target location you would like the element component to be rendered.

Other ways to declare components

There are many ways to declare components when using React.js, but there are two kinds of components, stateless components and stateful components.

Stateful

Class Type Components


class Cat extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
      humor: 'happy'
    }
  }
  render() {
    return(
      <div>
        <h1>{this.props.name}</h1>
        <p>
          {this.props.color}
        </p>
      </div>
    );
  }
}

Stateless Components

Functional Components (Arrow Function from ES6)


const Cat = props => {
  return (  
    <div>
      <h1>{props.name}</h1>
      <p>{props.color}</p>
    </div>;
  );
};

Implicit Return Components


const Cat = props => 
  <div>
    <h1>{props.name}</h1>
    <p>{props.color}</p>
  </div>;

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