Which JS events don't bubble up?

What are the situations in JS events that will not bubble?

Event bubbling (Event Bubbling) means that after an event is triggered on a certain element, the event will be passed upward along the DOM tree starting from the innermost element to the outermost element. This kind of transmission The method is called event bubbling. However, not all events can bubble up. There are some special cases where events will not bubble up. This article explains the situations in JavaScript where events don't bubble up.

1. Use the stopPropagation() method to prevent event bubbling
In JavaScript, you can use the stopPropagation() method to prevent the event from bubbling. That is, calling this method inside the event processing function can prevent Events bubble further upwards. If the stopPropagation() method is called inside the event handler, the event will no longer bubble up.

2. Some specific events will not bubble
In addition to using the stopPropagation() method to prevent events from bubbling, some specific events themselves will not bubble. These events include:

1. focus and blur events: events triggered when an element gains or loses focus. These events do not bubble.
2. Scroll event: An event triggered when an element is scrolled. This event will not bubble.
3. Load and unload events: Events triggered when the page is loaded or unloaded. These events do not bubble up.
4. Input event: An event triggered when the user enters text or changes the value of an element by pasting, etc. This event will not bubble.
5. submit event: an event triggered when the form is submitted. This event will not bubble up.

3. Unable to bubble up in event delegation
Event delegation (Event Delegation) is a commonly used way to bind events. The event is usually bound to the parent element, and then Events on child elements are handled through event bubbling. However, in event delegation, since the event is bound to the parent element, the event can only bubble up on the parent element and cannot bubble up to the child elements.

It should be noted that event delegation is not applicable in all situations. For example, some special events, such as the above-mentioned events that do not bubble up, cannot be processed through event delegation.

Summary
In JavaScript, event bubbling is an important mechanism, and most events will be delivered in a bubbling manner. However, there are some situations where events will not bubble, such as using the stopPropagation() method to prevent the event from bubbling, certain events themselves not bubbling, and bubbling in the event delegate. Understanding these situations is very important for both event handling and event delegation. Technicians should choose appropriate event processing methods based on specific needs and pay attention to the bubbling characteristics of events.

The above is the detailed content of Which JS events don't bubble up?. For more information, please follow other related articles on the PHP Chinese website!