jquery unblock default event

jQuery Unblock Default Event

In front-end development, the default event behavior is some special behavior that comes with DOM events. For example, the default behavior of clicking the a tag will jump to the corresponding link. Sometimes customers require some specific behaviors, and at this time developers need to prevent the default behavior of events to achieve customer needs. At certain times, the default behavior of blocking events needs to be released. This article will introduce how jQuery unblocks the default behavior of blocking events.

1. Default behavior

There is a special behavior in event processing, which is the default behavior. For example, the default behavior of the a tag is to jump to the corresponding link, the form submission behavior is to submit the form to the backend server, and the default behavior of the right-click menu is to pop up its own menu, etc. Default behavior is often blocked or modified to fulfill the developer's specific needs.

2. Event blocking

The function of event blocking is to prevent the default behavior of events. JavaScript events can generally be canceled, stopped, or blocked. Event default behavior can be prevented using the event.preventDefault() method. Please see the following example:

<a href="https://www.example.com" id="example">点击我跳转</a>

$('#example').click(function(event) {
  event.preventDefault();
});

In this way, when we click on the hyperlink, the default behavior will be prevented from jumping to the specified link.

3. Unblock

Sometimes, we don’t want to block the default behavior forever, but need to unblock it to achieve a specific function. At this time, we need to use the event.stopPropagation() and event.stopImmediatePropagtion() methods to unblock the default behavior of events.

event.stopPropagation() method can prevent the current event from propagating to the parent element from the bubbling process. But it does not affect other event listeners on the current element.

event.stopImmediatePropagation() The method can also prevent the current event from propagating to the parent element from the bubbling process. But unlike event.stopPropagation(), it will also block other event listeners on the current element.

Please see the following example:

<div id="parentNode">
  <p id="childNode">点击我</p>
</div>

$('#childNode').on('click', function(event) {
  event.stopImmediatePropagation();
  console.log('子元素的点击事件')
});

$('#parentNode').on('click', function(event) {
  console.log('父元素的点击事件')
});

In the above code, we bind click events to the child elements and parent elements respectively, and use event.stopImmediatePropagation() method prevents the default behavior of events on child elements. When we click on a child element, only the "click event of the child element" is output, and when we click on the parent element, the "click event of the child element" and "the click event of the parent element" are output.

4. Summary

Event default behaviors are some special behaviors that come with DOM events, which can prevent the default behavior of events. In some specific cases, we need to unblock the default behavior of events to achieve some specific functions. jQuery uses the event.stopPropagation() and event.stopImmediatePropagation() methods to relieve the default behavior of events to meet specific needs.

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