How does event bubbling and capturing work internally in JavaScript?

Event bubbling and capturing are critical concepts in JavaScript that define how events are handled within the DOM (Document Object Model). When an event occurs, such as a click or a key press, it propagates through the DOM tree, allowing handlers to respond at various stages of the event's lifecycle. Understanding these phases can help developers build more robust and interactive web applications.

1. **Event Capturing**: This phase starts from the root of the DOM and travels down to the targeted element. In this phase, events are first captured before reaching the target element where the event occurs. This is less commonly used but can be useful for specific applications where developers need to manage events at higher levels of the DOM.

2. **Event Bubbling**: After reaching the target element, the event then bubbles back up to the root of the DOM. This means that handlers attached to parent elements can also respond to the same event, effectively allowing multiple handlers to execute as the event moves up the tree. Bubbling is the default behavior in JavaScript and is commonly leveraged for event delegation.

Overall, understanding event bubbling and capturing can enhance event handling in JavaScript applications, enabling developers to write cleaner, easier-to-maintain code.