react绑定事件

绑定事件

• React事件名区别于DOM事件，以驼峰命名法
• JSX以函数的方式传递时间，而不是字符串

//HTML:<button onclick="activateLasers()">  Activate Lasers</button>//React:<button onClick={activateLasers}>  Activate Lasers</button>

• React中只能用preventDefault阻止默认行为，不可以用 return false

//HTML<a href="#" onclick="console.log('The link was clicked.'); return false">  Click me</a>//Reactfunction ActionLink() {  function handleClick(e) {    e.preventDefault();    console.log('The link was clicked.');  }  return (    <a href="#" onClick={handleClick}>      Click me    </a>  );}

• JSX回调中的this问题

必须在回调函数constructor中给事件回调函数绑定this,否则会报undefined

本章示例

constructor中绑定this,点击按钮切换ON和OFF

class Toggle extends React.Component {  constructor(props) {    super(props);    this.state = {isToggleOn: true};    // This binding is necessary to make `this` work in the callback    this.handleClick = this.handleClick.bind(this);  }  handleClick() {    this.setState(prevState => ({      isToggleOn: !prevState.isToggleOn    }));  }  render() {    return (      <button onClick={this.handleClick}>        {this.state.isToggleOn ? 'ON' : 'OFF'}      </button>    );  }}ReactDOM.render(  <Toggle />,  document.getElementById('root'));