深入了解React中的合成事件

1 事件三個階段 捕獲、目標、處理 （具體百度，后面有空補全）

2 示例

import React from "react"; class Test extends React.Component {  parentRef;  childRef;  constructor(props) {    super(props);    this.parentRef = React.createRef();    this.childRef = React.createRef();  }  componentDidMount() {    document.addEventListener(      "click",      () => {console.log(`document原生事件捕獲`);      },      true    );    document.addEventListener("click", () => {      console.log(`document原生事件冒泡`);    });    this.parentRef.current.addEventListener(      "click",      () => {console.log(`父元素原生事件捕獲`);      },      true    );    this.parentRef.current.addEventListener("click", () => {      console.log(`父元素原生事件冒泡`);    });    this.childRef.current.addEventListener(      "click",      () => {console.log(`子元素原生事件捕獲`);      },      true    );    this.childRef.current.addEventListener("click", () => {      console.log(`子元素原生事件冒泡`);    });  }  handleParentBubble = () => {    console.log(`父元素React事件冒泡`);  };  handleChildBubble = (e) => {    console.log(`子元素React事件冒泡`);  };  handleParentCapture = () => {    console.log(`父元素React事件捕獲`);  };  handleChileCapture = () => {    console.log(`子元素React事件捕獲`);  };  render() {    return (      <divref={this.parentRef}onClick={this.handleParentBubble}onClickCapture={this.handleParentCapture}      ><div  ref={this.childRef}  onClick={this.handleChildBubble}  onClickCapture={this.handleChileCapture}>  事件處理測試</div>      </div>    );  }} export default Test;

執行順序

只留子元素修改代碼

import React from "react"; class Test extends React.Component {  parentRef;  childRef;  constructor(props) {    super(props);    this.parentRef = React.createRef();    this.childRef = React.createRef();  }  componentDidMount() {    document.addEventListener(      "click",      () => {console.log(`document原生事件捕獲`);      },      true    );    document.addEventListener("click", () => {      console.log(`document原生事件冒泡`);    });    // this.parentRef.current.addEventListener(    //   "click",    //   () => {    //     console.log(`父元素原生事件捕獲`);    //   },    //   true    // );    // this.parentRef.current.addEventListener("click", () => {    //   console.log(`父元素原生事件冒泡`);    // });    this.childRef.current.addEventListener(      "click",      () => {console.log(`子元素原生事件捕獲`);      },      true    );    this.childRef.current.addEventListener("click", () => {      console.log(`子元素原生事件冒泡`);    });  }  // handleParentBubble = () => {  //   console.log(`父元素React事件冒泡`);  // };  handleChildBubble = (e) => {    console.log(`子元素React事件冒泡`);  };  // handleParentCapture = () => {  //   console.log(`父元素React事件捕獲`);  // };  handleChileCapture = () => {    console.log(`子元素React事件捕獲`);  };  render() {    return (      <divref={this.childRef}onClick={this.handleChildBubble}onClickCapture={this.handleChileCapture}      >事件處理測試      </div>    );    return (      <divref={this.parentRef}onClick={this.handleParentBubble}onClickCapture={this.handleParentCapture}      ><div  ref={this.childRef}  onClick={this.handleChildBubble}  onClickCapture={this.handleChileCapture}>  事件處理測試</div>      </div>    );  }} export default Test;

document原生事件捕獲--》子元素React事件捕獲--》子元素原生事件捕獲--》子元素原生事件冒泡--》子元素React事件冒泡--》document原生事件冒泡

從這個執行順序來看，react事件捕獲執行比原生事件捕獲早，但是原生事件冒泡執行比react事件冒泡快。

所有的react捕獲事件執行完畢之后才會去執行原生的捕獲事件（document原生事件捕獲最先執行）

3 子元素阻止react事件冒泡

e.stopPropagation();

import React from "react"; class Test extends React.Component {  parentRef;  childRef;  constructor(props) {    super(props);    this.parentRef = React.createRef();    this.childRef = React.createRef();  }  componentDidMount() {    document.addEventListener(      "click",      () => {console.log(`document原生事件捕獲`);      },      true    );    document.addEventListener("click", () => {      console.log(`document原生事件冒泡`);    });    this.parentRef.current.addEventListener(      "click",      () => {console.log(`父元素原生事件捕獲`);      },      true    );    this.parentRef.current.addEventListener("click", () => {      console.log(`父元素原生事件冒泡`);    });    this.childRef.current.addEventListener(      "click",      () => {console.log(`子元素原生事件捕獲`);      },      true    );    this.childRef.current.addEventListener("click", () => {      console.log(`子元素原生事件冒泡`);    });  }  handleParentBubble = () => {    console.log(`父元素React事件冒泡`);  };  handleChildBubble = (e) => {    e.stopPropagation();    console.log(`子元素React事件冒泡`);  };  handleParentCapture = () => {    console.log(`父元素React事件捕獲`);  };  handleChileCapture = () => {    console.log(`子元素React事件捕獲`);  };  render() {    return (      <divref={this.parentRef}onClick={this.handleParentBubble}onClickCapture={this.handleParentCapture}      ><div  ref={this.childRef}  onClick={this.handleChildBubble}  onClickCapture={this.handleChileCapture}>  事件處理測試</div>      </div>    );  }} export default Test;

執行順序

e.stopPropagation()只能阻止react合成事件的冒泡和document原生事件冒泡，并不能阻止自己和父元素原生事件的冒泡。

e.nativeEvent.stopImmediatePropagation()只能阻止document原生事件冒泡。

e.preventDefault()和不執行一樣

e.nativeEvent.stopPropagation()只能阻止document原生事件冒泡。

如果我們在子原生的原聲事件里面阻止冒泡，都阻止了。

import React from "react"; class Test extends React.Component {  parentRef;  childRef;  constructor(props) {    super(props);    this.parentRef = React.createRef();    this.childRef = React.createRef();  }  componentDidMount() {    document.addEventListener(      "click",      () => {console.log(`document原生事件捕獲`);      },      true    );    document.addEventListener("click", () => {      console.log(`document原生事件冒泡`);    });    this.parentRef.current.addEventListener(      "click",      () => {console.log(`父元素原生事件捕獲`);      },      true    );    this.parentRef.current.addEventListener("click", () => {      console.log(`父元素原生事件冒泡`);    });    this.childRef.current.addEventListener(      "click",      () => {console.log(`子元素原生事件捕獲`);      },      true    );    this.childRef.current.addEventListener("click", (e) => {      e.stopPropagation();      console.log(`子元素原生事件冒泡`);    });  }  handleParentBubble = () => {    console.log(`父元素React事件冒泡`);  };  handleChildBubble = (e) => {    console.log(`子元素React事件冒泡`);  };  handleParentCapture = () => {    console.log(`父元素React事件捕獲`);  };  handleChileCapture = () => {    console.log(`子元素React事件捕獲`);  };  render() {    return (      <divref={this.parentRef}onClick={this.handleParentBubble}onClickCapture={this.handleParentCapture}      ><div  ref={this.childRef}  onClick={this.handleChildBubble}  onClickCapture={this.handleChileCapture}>  事件處理測試</div>      </div>    );  }} export default Test;

執行順序

在子元素的原聲事件里面，阻止了所有的冒泡。同時也阻止了react事件。

在父元素原生事件中阻止冒泡

import React from "react"; class Test extends React.Component {  parentRef;  childRef;  constructor(props) {    super(props);    this.parentRef = React.createRef();    this.childRef = React.createRef();  }  componentDidMount() {    document.addEventListener(      "click",      () => {console.log(`document原生事件捕獲`);      },      true    );    document.addEventListener("click", () => {      console.log(`document原生事件冒泡`);    });    this.parentRef.current.addEventListener(      "click",      () => {console.log(`父元素原生事件捕獲`);      },      true    );    this.parentRef.current.addEventListener("click", (e) => {      e.stopPropagation();      console.log(`父元素原生事件冒泡`);    });    this.childRef.current.addEventListener(      "click",      () => {console.log(`子元素原生事件捕獲`);      },      true    );    this.childRef.current.addEventListener("click", (e) => {      console.log(`子元素原生事件冒泡`);    });  }  handleParentBubble = () => {    console.log(`父元素React事件冒泡`);  };  handleChildBubble = (e) => {    console.log(`子元素React事件冒泡`);  };  handleParentCapture = () => {    console.log(`父元素React事件捕獲`);  };  handleChileCapture = () => {    console.log(`子元素React事件捕獲`);  };  render() {    return (      <divref={this.parentRef}onClick={this.handleParentBubble}onClickCapture={this.handleParentCapture}      ><div  ref={this.childRef}  onClick={this.handleChildBubble}  onClickCapture={this.handleChileCapture}>  事件處理測試</div>      </div>    );  }} export default Test;

執行順序

父元素原生事件中阻止冒泡阻止了react事件

阻止document原生事件的冒泡并不會阻止了react事件

 document.addEventListener("click", (e) => {      e.stopPropagation();      console.log(`document原生事件冒泡`); });

結論

react捕獲事件快于原生捕獲事件的執行

react冒泡事件慢于原生冒泡事件的執行

原生冒泡事件會阻止react事件。

以上就是深入了解React中的合成事件的詳細內容，更多關于React合成事件的資料請關注其它相關文章！