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深入了解React中的合成事件_React

作者：跑跑快跑 ? 更新時間： 2023-05-23 編程語言

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 (
      <div
        ref={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 (
      <div
        ref={this.childRef}
        onClick={this.handleChildBubble}
        onClickCapture={this.handleChileCapture}
      >
        事件處理測試
      </div>
    );
    return (
      <div
        ref={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 (
      <div
        ref={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 (
      <div
        ref={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 (
      <div
        ref={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。

原文鏈接：https://blog.csdn.net/qq_33715850/article/details/129101129

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