What is event bubbling?

Event bubbling is a concept in JavaScript related to how events propagate through the Document Object Model (DOM) tree. When an event is triggered on a specific element, such as a click on a button, that event doesn't just affect the element itself—it moves, or "bubbles," upward through its parent elements in the DOM hierarchy. Specifically, event bubbling means that after an event occurs on the target element, the event is then dispatched to its parent element, then to the parent's parent, and so on, all the way up to the root of the document (usually the `` element). This allows multiple elements in the DOM to respond to the same event, enabling things like event delegation, where you attach a single event listener to a parent element to handle events from many child elements efficiently. For example, if you have a nested structure like a `` inside a ``, and you click the button, the click event first fires on the button itself, then bubbles up to the ``, and then further up the DOM tree unless the event propagation is stopped using methods like `event.stopPropagation()`. Understanding event bubbling is important for managing how events are handled in complex web applications, preventing unwanted side effects, and optimizing event listener usage.

Event bubbling is a concept in JavaScript related to how events propagate through the Document Object Model (DOM) tree. When an event occurs on a particular element, such as a click on a button, that event doesn’t just affect the target element; it also "bubbles up" through its ancestor elements all the way up to the root of the document (usually the `` element). Here’s how it works: suppose you click a button inside a ``, which is inside another container element. The click event first triggers on the button itself (the event target), then on the button’s parent ``, then on the next ancestor, and so on, until it reaches the topmost element. Each ancestor has the opportunity to respond to the event during this bubbling phase. Event bubbling is useful because it allows event delegation — you can attach a single event listener to a parent element instead of adding listeners to multiple child elements. This can improve performance and simplify code. For example, instead of adding click handlers to every item in a list, you add one listener to the list container and handle clicks based on the event target. If you want to stop the event from bubbling up to ancestor elements, you can call `event.stopPropagation()` inside your event handler. This prevents further propagation of the event in the bubbling phase. In summary, event bubbling is the process where an event starts at the most specific element (the target) and then propagates upward through the DOM tree, allowing multiple elements to respond to the same event in a hierarchical manner.