render为什么不用传参

Question

class App extends React.Component {    constructor(props){        // 必须要传递参数        super(props)        this.state = {            text: this.props.text        }    }        render() {        return (            // render不用传props            <div>{this.props.children}</div>        )    }}constructor和render内部this都指向组件实例，只要constructor内部要读取props就要写明这个参数，但是render不用，为什么呢？

Answer 1

es6:

There is only one reason when one needs to pass props to super():

When you want to access this.props in constructor.

(Which is probably redundant since you already have a reference to it.)

所以只有在构造器constructor内使用this.props的时候 
才写super(props), 不使用传入props也没错.

es5:

React.createClass({
  getInitialState(){     return {
         text: this.props.text
     }
  },
  render(){    return ...
  }
})