Event bubbling is an essential concept in JavaScript. It is also a widely accessed terminology in JavaScript during the event flow. Every event flow process completes with the help of three major concepts – event capturing, event target, and event bubbling. Events are highly responsible for the interaction of JavaScript with HTML web pages.
In general, an event is an act that occurs by someone. The definition of the event is the same in web development. Listeners subscribe to the events that happen if a particular event is fired. Event flow is nothing but the order the event receives on the web page. A professional web developer should discuss finding the perfect way suitable for the event flow.
Two potential ways to ensure the trouble-free event flow are event capturing and event bubbling. Here, you will understand in-depth about the event bubbling.
What To Know About Event Bubbling
Event bubbling is the event that begins from the target or deepest element to its parents and all its ancestors on the way to the bottom to top. All the modern browsers now have the event bubbling as their default way of event flow. It helps the browsers to avoid potential hassles and troubles.
In short, it is the event propagation method where the event initially triggers its innermost target elements. After that, it triggers the ancestors of the target elements in the similar nesting hierarchy until it reaches the outermost document object. All the events bubble by default.
Syntax
addEventListener(type, listener, useCapture)
Here,
- Type indicates the type of event
- Listener Refers to the function needed to call whenever the event of the specified type happens
- user capture mentions the Boolean value. The userCapture is false by default because it is in the bubbling phase.
How To Implement Event Bubbling
All the event handlers consider the event bubbling as the default method of event handling. However, the user can choose the way of propagation manually by mentioning that as the last parameter in the addEventListener() of the element in JavaScript.
Syntax:
addEventListener(“type”, “Listener”, “CaptureMode”)
Even bubbling will handle the event when the capture mode is false. In case the CaptureMode is true, event capturing will handle the event. Whenever the user does not indicate any value of the CaptureMode argument, it is considered event bubbling (default).
Almost all the browsers support both events capturing and event bubbling. In JavaScript, the event property called bubbles checks whether the event is bubbling. It returns the boolean value (true or false) based on whether the event can bubble up to the ancestor elements in the DOM structure.
What Are The Events Not A Bubble?
Even though all the events bubble by default, certain events do not bubble. Here are such kinds of exception events, which do not bubble.
- focus
- blur
- mouseleave
- DOMNodeInsertedIntoDocument
- load, unload, error, abort
Generally, the capability of bubbling defines when constructing the event through bubbles: boolean option. You may get a doubt whether the non-bubble events capture. As long as the browser does not support the event capture, the non-bubble events will capture.
Significant Uses Of The Event Bubbling
Implementing the event bubbling concept becomes necessary to handle cases where one event has more than a single handler. Within the single event handler, you can handle any number of child elements quickly and effortlessly.
The registration of the default functions available in the program is the prominent use of the event bubbling. If the event is registered, it passes up the chain of its parents until someone handles the event. It indicates that you will define the single handler on the top-level element to handle all the significant events within it.
How To Prevent Events Bubbling
Do you know that stopping the single trigger on one element that leads to several triggers on the parents is useful? Usually, the event on the DOM element often propagates to all of its ancestors unless it is stopped. So, even though there is no requirement to prevent event bubbling, it is beneficial in that moment.
When you stop the propagation, it prevents the event handlers from interfering. JavaScript renders the following methods to prevent the event from bubbling in such a case. It helps you to avoid any issues and hassles.
- stopPropagation()
The stopPropagation() method stops the future propagation of any specific event to its ancestors. It involves the event handler of the target element alone. Even though all W3C compliant browsers support the method, the internet explorer below version 9 needs the historical alias cancer bubble. Here is the syntax.
event .cancelBubble = true:
For all the W3C compliant browsers, the syntax will be the following.
event .stopProgpagation();
- stopImmediatePropagation()
It is one of the best methods to stop the event from bubbling. Apart from stopping the further propagation, it also stops other handlers of the target event from running. The same event can have several independent handlers in the DOM. Thus, stopping the execution of a single event handler does not affect other handlers of a similar target.
However, the stopImmediatePropagation() method prevents the execution of all the handlers of the same target. It means the method does not allow any event handler to execute.
Syntax
event .stopImmediatePropagation();
Canceling the event itself is another vital approach to stop it from bubbling. But, the method prevents the target handler execution. So, you should access the specific method suitable for your needs.
It would help if you were careful when stopping events from executing and propagating because you will not be sure that you sometimes need the specific event in the parent’s element. Or else, you may need different things. It is much better to think twice and seek the experts’ advice before stopping the event bubbling.
After knowing in-depth about the event bubbling, do you have specific queries and doubts? Instead of worrying, you can get assistance from the professionals at JDM Web Technologies. The experts have immense knowledge and experience in event bubbling. Thus, they help you to make the right decision.
