mouseenter

Mouseenter is a mouse event in the web browser DOM that fires when the pointer enters the boundary of a specified element. It is part of the standard set of mouse events used to respond to pointer movement and is supported by modern browsers.

Unlike the related mouseover event, mouseenter does not bubble up through the DOM and generally fires only when the pointer enters the element to which the handler is attached. It does not repeatedly fire when the pointer moves among the element’s descendants. This makes mouseenter convenient for triggering actions once when a user first hovers over a region, without reacting to every movement over inner elements. If you need to detect movement across nested elements or want bubbling behavior, mouseover and mouseout or event delegation can be used as alternatives. CSS hover styling can also achieve similar visual effects without JavaScript.

Usage typically involves listening for the event with addEventListener or an onmouseenter attribute, for example: element.addEventListener('mouseenter', handler). The event object is a MouseEvent and provides standard properties such as clientX, clientY, screenX, screenY, and relatedTarget (the element the pointer came from). Cross-browser support is strong in modern environments; on touch devices or pointerless contexts, mouseenter may not fire. In accessibility-conscious design, hover-based interactions should not be relied on exclusively, and keyboard or focus-based mechanisms should be provided.