react生命周期

class Counter extends React.Component {  static defaultProps = {    name:'plus'  }  constructor(props){     super(props)     this.state = {       number:0     }     console.log('构造函数')  }  componentWillMount(){    console.log('组件将要加载')  }  componentDidMount(){    console.log('组件挂载完成')  }  handleClick = () => {    this.setState({      number:this.state.number+1    })  }  shouldComponentUpdate(nextProps,nextState){    console.log('组件是否更新')    return nextState.number % 2    ///如果此函数种返回了false 就不会调用render方法了  }  componentWillUpdate(){    console.log('组件将要更新')  }  componentDidUpdate(){    console.log('组件更新完成')  }  render(){    console.log('render')    return (      
    
        
     
{this.state.number}
        {this.state.number > 3 ? null :
     
      }          
      +      
     
    
    )  }}class ChildCounter extends React.Component{  componentWillUnMount(){    console.log('组件将要卸载componentWillUnmount')  }  componentWillMount(){    console.log('child componentWillMount')  }  render(){    console.log('child-render')    return (
    
           {this.props.n}    
    
)  }  componentDidMount(){    console.log('child componentDidMount')  }  componentWillReceiveProps(newProps){ // 第一次不会执行，之后属性更新时才会执行    console.log('child componentWillReceiveProps')  }  shouldComponentUpdate(nextProps,nextState){    return nextProps.n % 3; //子组件判断接收的属性 是否满足更新条件 为true则更新  }}ReactDOM.render(
    ,document.getElementById('root'))