Detailed explanation of JS bubbling events and event capture examples-JS Tutorial-php.cn

Detailed explanation of JS bubbling events and event capture examples

高洛峰

Release： 2016-12-05 11:41:47

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This article analyzes JS bubbling events and event capture with examples. Share it with everyone for your reference, the details are as follows:

Case

<!DOCTYPE html>
<html>
<head>
  <title>冒泡事件</title>
  <script type="text/javascript">
    window.onload = function(){
      window.onclick = function(){
        alert("Window"); // 顶级
      };
      document.onclick = function(){
        alert("Document"); // 次顶级
      };
      document.documentElement.onclick = function(){
        alert("Html"); // 次次顶级
      };
      document.body.onclick = function(){
        alert("Body"); // 次次次顶级
      };
      document.getElementById("myDiv").onclick = function(){
        alert("Div"); // 最先执行，并且会传递到上一层。点击两次，则按顺序执行两次。如果上级也有点击事件的话
      };
    }
  </script>
</head>
<body>
  <div id="myDiv">点我</div>
</body>
</html>

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Summary

1. Click myDiv. The order is Div-Body-Html-Document-Window

2. Click on other blank places. The order is Html-Document-Window

3. Click twice in succession and it will be executed twice in sequence

4. The premise of bubbling is that the parent also defines the corresponding event

Let’s look at a more complex example

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>事件捕捉</title>
  <script type="text/javascript">
    window.onload = function(){
      window.addEventListener("click", function(){
        alert("Window - true");
      }, true); // true - 事件句柄在捕获阶段执行 ,false- false- 默认。事件句柄在冒泡阶段执行
      document.addEventListener("click", function(){
        alert("Document - true");
      }, true);
      document.documentElement.addEventListener("click", function(){
        alert("Html - true");
      }, true);
      document.body.addEventListener("click", function(){
        alert("Body - true");
      }, true);
      document.getElementById("myDiv").addEventListener("click", function(){
        alert("Div - true");
      }, true);
      window.addEventListener("click", function(){
        alert("Window - false");
      }, false); // true - 事件句柄在捕获阶段执行 ,false- false- 默认。事件句柄在冒泡阶段执行
      document.addEventListener("click", function(){
        alert("Document - false");
      }, false);
      document.documentElement.addEventListener("click", function(){
        alert("Html - false");
      }, false);
      document.body.addEventListener("click", function(){
        alert("Body - false");
      }, false);
      document.getElementById("myDiv").addEventListener("click", function(){
        alert("Div - false");
      }, false);
      window.onclick = function(){
        alert("Window - click"); // 顶级
      };
      document.onclick = function(){
        alert("Document - click"); // 次顶级
      };
      document.documentElement.onclick = function(){
        alert("Html - click"); // 次次顶级
      };
      document.body.onclick = function(){
        alert("Body - click"); // 次次次顶级
      };
      document.getElementById("myDiv").onclick = function(){
        alert("Div - click"); // 最先执行，并且会传递到上一层。点击两次，则按顺序执行两次。如果上级也有点击事件的话
      };
    }
  </script>
</head>
<body>
  <div id="myDiv">点我</div>
</body>
</html>

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Summary

1. The execution result of the click is

Window - true

Document - true

Html - true

Body - true

Div - true

Div - false

Div- click

Body - false

Body - click

Html - false

Html - click

Document - false

Document - click

Window - false

Window - click

2. Sequence and js code sequence It's irrelevant

3. Even if the click event is not defined, the click event can still be captured. As long as it is clicked, it can be captured

Reform again to prevent bubbling

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>事件捕捉</title>
  <script type="text/javascript">
    window.onload = function(){
      document.addEventListener("click", function(){
        alert("Document - true");
      }, true);
      window.addEventListener("click", function(){
        alert("Window - true");
      }, true); // true - 事件句柄在捕获阶段执行 ,false- false- 默认。事件句柄在冒泡阶段执行
      document.documentElement.addEventListener("click", function(){
        alert("Html - true");
      }, true);
      document.body.addEventListener("click", function(){
        alert("Body - true");
      }, true);
      document.getElementById("myDiv").addEventListener("click", function(){
        alert("Div - true");
      }, true);
      window.addEventListener("click", function(){
        alert("Window - false");
      }, false); // true - 事件句柄在捕获阶段执行 ,false- false- 默认。事件句柄在冒泡阶段执行
      document.addEventListener("click", function(){
        alert("Document - false");
      }, false);
      document.documentElement.addEventListener("click", function(){
        alert("Html - false");
      }, false);
      document.body.addEventListener("click", function(){
        alert("Body - false");
      }, false);
      document.getElementById("myDiv").addEventListener("click", function(){
        alert("Div - false");
      }, false);
      window.onclick = function(){
        alert("Window - click"); // 顶级
      };
      document.onclick = function(){
        alert("Document - click"); // 次顶级
      };
      document.documentElement.onclick = function(){
        alert("Html - click"); // 次次顶级
      };
      document.body.onclick = function(){
        alert("Body - click"); // 次次次顶级
      };
      document.getElementById("myDiv").onclick = function(){
        alert("Div - click"); // 最先执行，并且会传递到上一层。点击两次，则按顺序执行两次。如果上级也有点击事件的话
        event.stopPropagation(); // 阻止冒泡
      };
    }
  </script>
</head>
<body>
  <div id="myDiv">点我</div>
</body>
</html>

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Summary

Window - true

Document - true

Html - true

Body - true

Div - true

Div - false

Div - click

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