Themouseenter event is fired at anElement when a pointing device (usually a mouse) is initially moved so that its hotspot is within the element at which the event was fired.

Note that "moving into an element" refers to the element's position in the DOM tree, not to its visual position. For example, if a child element is positioned so it is placed outside its parent, then moving into the child element will triggermouseenter on the parent element, even though the pointer is still outside the bounds of the parent element.

Syntax

Use the event name in methods likeaddEventListener(), or set an event handler property.

addEventListener("mouseenter", (event) => { })onmouseenter = (event) => { }

Event type

AMouseEvent. Inherits fromUIEvent andEvent.

Event properties

This interface also inherits properties of its parents,UIEvent andEvent.

MouseEvent.altKeyRead only

Returnstrue if thealt key was down when the mouse event was fired.

MouseEvent.buttonRead only

The button number that was pressed (if applicable) when the mouse event was fired.

MouseEvent.buttonsRead only

The buttons being pressed (if any) when the mouse event was fired.

MouseEvent.clientXRead only

The X coordinate of the mouse pointer inviewport coordinates.

MouseEvent.clientYRead only

The Y coordinate of the mouse pointer inviewport coordinates.

MouseEvent.ctrlKeyRead only

Returnstrue if thecontrol key was down when the mouse event was fired.

MouseEvent.layerXNon-standardRead only

Returns the horizontal coordinate of the event relative to the current layer.

MouseEvent.layerYNon-standardRead only

Returns the vertical coordinate of the event relative to the current layer.

MouseEvent.metaKeyRead only

Returnstrue if themeta key was down when the mouse event was fired.

MouseEvent.movementXRead only

The X coordinate of the mouse pointer relative to the position of the lastmousemove event.

MouseEvent.movementYRead only

The Y coordinate of the mouse pointer relative to the position of the lastmousemove event.

MouseEvent.offsetXRead only

The X coordinate of the mouse pointer relative to the position of the padding edge of the target node.

MouseEvent.offsetYRead only

The Y coordinate of the mouse pointer relative to the position of the padding edge of the target node.

MouseEvent.pageXRead only

The X coordinate of the mouse pointer relative to the whole document.

MouseEvent.pageYRead only

The Y coordinate of the mouse pointer relative to the whole document.

MouseEvent.relatedTargetRead only

The secondary target for the event, if there is one.

MouseEvent.screenXRead only

The X coordinate of the mouse pointer inscreen coordinates.

MouseEvent.screenYRead only

The Y coordinate of the mouse pointer inscreen coordinates.

MouseEvent.shiftKeyRead only

Returnstrue if theshift key was down when the mouse event was fired.

MouseEvent.mozInputSourceNon-standardRead only

The type of device that generated the event (one of theMOZ_SOURCE_* constants).This lets you, for example, determine whether a mouse event was generated by an actual mouse or by a touch event (which might affect the degree of accuracy with which you interpret the coordinates associated with the event).

MouseEvent.webkitForceNon-standardRead only

The amount of pressure applied when clicking.

MouseEvent.xRead only

Alias forMouseEvent.clientX.

MouseEvent.yRead only

Alias forMouseEvent.clientY.

Usage notes

Though similar tomouseover,mouseenter differs in that it doesn'tbubble and it isn't sent to any descendants when the pointer is moved from one of its descendants' physical space to its own physical space. Other than that, enter and over events for the same situation are dispatched at the same time, if appropriate.

Behavior ofmouseenter events

This describes the mouseenter events received by each of four concentric divs with no padding or margin, so the events all happen at the same time:Onemouseenter event is sent to each element of the hierarchy when entering them. Here 4 events are sent to the four elements of the hierarchy when the pointer reaches the text.

Behavior ofmouseover events

A singlemouseover event is sent to the deepest element of the DOM tree, then it bubbles up the hierarchy until it is canceled by a handler or reaches the root.

With deep hierarchies, the number ofmouseenter events sent can be quite huge and cause significant performance problems. In such cases, it is better to listen formouseover events.

Combined with the correspondingmouseleave (which is fired at the element when the mouse exits its content area), themouseenter event acts in a very similar way to the CSS:hover pseudo-class.

Examples

Themouseover documentation has an example illustrating the difference betweenmouseover andmouseenter.

mouseenter

The following trivial example uses themouseenter event to change the border on thediv when the mouse enters the space allotted to it. It then adds an item to the list with the number of themouseenter ormouseleave event.

HTML

<div>  <ul>    <li>No events yet!</li>  </ul></div>

CSS

Styling thediv to make it more visible.

#mouseTarget {  box-sizing: border-box;  width: 15rem;  border: 1px solid #333333;}

JavaScript

let enterEventCount = 0;let leaveEventCount = 0;const mouseTarget = document.getElementById("mouseTarget");const unorderedList = document.getElementById("unorderedList");mouseTarget.addEventListener("mouseenter", (e) => {  mouseTarget.style.border = "5px dotted orange";  enterEventCount++;  addListItem(`This is mouseenter event ${enterEventCount}.`);});mouseTarget.addEventListener("mouseleave", (e) => {  mouseTarget.style.border = "1px solid #333333";  leaveEventCount++;  addListItem(`This is mouseleave event ${leaveEventCount}.`);});function addListItem(text) {  // Create a new text node using the supplied text  const newTextNode = document.createTextNode(text);  // Create a new li element  const newListItem = document.createElement("li");  // Add the text node to the li element  newListItem.appendChild(newTextNode);  // Add the newly created list item to list  unorderedList.appendChild(newListItem);}

Result

Specifications

Browser compatibility

See also

• Learn: Introduction to events
• mousedown
• mouseup
• mousemove
• click
• dblclick
• mouseover
• mouseout
• mouseleave
• contextmenu
• pointerenter