What is preventing event bubbling?

Preventing event bubbling refers to the process of programmatically preventing events from being passed from child elements to parent elements or ancestor elements in web development. Event bubbling is in a nested element hierarchy, when an event fires on a child element, it is automatically propagated up to the parent element, and then to ancestor elements, until it reaches the top-most element. Preventing event bubbling is a technology commonly used in web development. It can better control and manage the propagation of events. By preventing event bubbling, unnecessary event triggering and processing can be avoided, improving user experience and code efficiency.

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

Preventing event bubbling refers to the process of programmatically preventing events from being passed from child elements to parent elements or ancestor elements in web development. Event bubbling means that in a nested element hierarchy, when an event fires on a child element, it is automatically propagated up to the parent element, and then to ancestor elements, until it reaches the top-most element.

The event bubbling mechanism allows events of multiple child elements to be monitored on a parent element, thereby achieving a simple and efficient event management. However, in some cases we may need to prevent events from bubbling to avoid unnecessary event firing or processing.

Preventing event bubbling can be achieved by using the methods provided by JavaScript in the event handling function. The following are several commonly used methods:

1. stopPropagation() method: This is the most common and recommended method, which can prevent events from continuing to propagate to parent elements or ancestor elements. Call this method in the event handler to stop event bubbling. For example:

   function handleClick(event) {
     event.stopPropagation();
     // 处理事件
   }

2. cancelBubble attribute: This is an earlier method that has been replaced by the stopPropagation() method, but can still be used in some cases. This property is used in Internet Explorer to prevent event bubbling by setting it to true. For example:

   function handleClick(event) {
     event.cancelBubble = true;
     // 处理事件
   }

It should be noted that preventing event bubbling will only stop event propagation, but will not prevent the event's default behavior. If you need to prevent the event's default behavior at the same time, you can use the preventDefault() method.

There are various application scenarios for preventing event bubbling. For example, when a button is nested in a parent element that contains a click event, two events may be triggered when the button is clicked: the button's click event and the parent element's click event. If you do not want the click event of the parent element to be triggered, you can call the stopPropagation() method in the button's click event handler.

To summarize, preventing event bubbling is a technique commonly used in web development, which can help us better control and manage the propagation of events. By preventing event bubbling, we can avoid unnecessary event triggering and processing, improving user experience and code efficiency.

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