What are the ways to prevent events from bubbling up?

Methods to prevent event bubbling include the "stopPropagation()" method, the "cancelBubble" attribute, the "return false" statement, the "stopImmediatePropagation()" method and the "preventDefault()" method in conjunction with "stopPropagation()" method. Developers should choose an appropriate method based on specific needs and browser compatibility. Proper use of bubbling prevention methods can improve interaction effects.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

Preventing event bubbling is one of the common requirements in web development. It can prevent events from being passed to parent elements and other ancestor elements, and only trigger the event handler of the current element. In actual development, there are many ways to prevent events from bubbling. This article will detail five commonly used methods to prevent event bubbling.

1. stopPropagation() method

The stopPropagation() method is the most commonly used and simple method to prevent events from bubbling. This method can prevent the event from bubbling by calling the stopPropagation() function of the event object. An example is as follows:

   elem.addEventListener('click', function(event){
      event.stopPropagation();
   });

In the above example, a click event handler is bound to the element through the addEventListener() function, and then the stopPropagation() method is called in the handler function. After calling this method, the event will no longer be passed to the parent element, and only the click event of the current element will be triggered.

2. cancelBubble attribute

The cancelBubble attribute is a method provided by early IE browsers to prevent event bubbling, and is still compatible with most modern browsers. This property will be set to true in the event handling function to prevent the event from bubbling. An example is as follows:

   elem.onclick = function(event){
      event.cancelBubble = true;
   };

In the above example, the bubbling delivery of click events is prevented by setting the cancelBubble property to true.

3. return false statement

In some cases, if you want to prevent the default behavior of the event and prevent the event from bubbling at the same time, you can use the method of returning false. An example is as follows:

   elem.onclick = function(event){
      // 阻止事件冒泡
      event.stopPropagation();
      // 阻止事件默认行为
      return false;
   };

In the above example, both event bubbling and the default behavior of the event are prevented by returning false in the event handling function. It should be noted that return false can only be used when directly binding event processing functions, and cannot be used for event binding with the addEventListener() function.

4. stopImmediatePropagation() method

The stopImmediatePropagation() method is very similar to the stopPropagation() method and can be used to prevent event bubbling, but it also has an additional feature - it can Prevents the execution of other event handlers on the same element. An example is as follows:

   elem.addEventListener('click', function(event){
      console.log('事件处理函数1');
      event.stopImmediatePropagation();
   });
   elem.addEventListener('click', function(event){
      console.log('事件处理函数2');
   });

In the above example, by calling the stopImmediatePropagation() method, event handling function 1 will prevent the event from bubbling, and other event handling functions will not be executed. Therefore, only "Event Handling Function 1" will be output, but "Event Handling Function 2" will not be output.

5. The preventDefault() method cooperates with the stopPropagation() method

In some cases, we not only want to prevent the event from bubbling, but also want to prevent the default behavior of the event (such as prohibiting link clicks Jump or form submission, etc.). At this time, you can use the preventDefault() method and the stopPropagation() method in combination. An example is as follows:

   elem.addEventListener('click', function(event){
      event.preventDefault();
      event.stopPropagation();
   });

In the above example, by calling the preventDefault() method, you can prevent the default behavior of the click event, such as link jump or form submission. Calling the stopPropagation() method at the same time can prevent the event from bubbling and ensure that only the event handler of the current element is triggered.

It should be noted that although the above methods can be used to prevent event bubbling, in actual use, you should choose carefully when to use it. Excessive abuse of preventing event bubbling may result in the event not being passed to the parent element or other processing functions, affecting the user experience. Therefore, the above methods should be used only in scenarios where it is really necessary to prevent event bubbling, and the applicable method should be reasonably selected based on the needs.

In summary, methods to prevent event bubbling include using the stopPropagation() method, cancelBubble attribute, return false statement, stopImmediatePropagation() method, and preventDefault() method in conjunction with the stopPropagation() method. Each method has its own applicable scenarios, and developers should choose based on specific needs and browser compatibility. At the same time, reasonable use of methods to prevent event bubbling can improve interaction effects and user experience.

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