text: var Input = React.createClass({
    getInitialState(){
      return {val:'请输入...'};
    },
    handleChange(event){
      this.setState({val:event.target.value})
    },
    render(){
        return (
            <div>
                <input type="text" onChange={this.handleChange} value={this.state.val}/>
                <p>{this.state.val}</p>
            </div>
        )
    }
  });
  ReactDOM.render(<Input/>,document.querySelector('#app'));