Element: mouseenter event
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The mouseenter
event is fired at an Element
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 event" 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 trigger mouseenter
on the parent element, even though the pointer is still outside the bounds of the parent element.
Syntax
Use the event name in methods like addEventListener()
, or set an event handler property.
addEventListener("mouseenter", (event) => {});
onmouseenter = (event) => {};
Event type
A MouseEvent
. Inherits from UIEvent
and Event
.
Event properties
This interface also inherits properties of its parents, UIEvent
and Event
.
MouseEvent.altKey
Read only-
Returns
true
if the alt key was down when the mouse event was fired. -
The button number that was pressed (if applicable) when the mouse event was fired.
-
The buttons being pressed (if any) when the mouse event was fired.
MouseEvent.clientX
Read only-
The X coordinate of the mouse pointer in viewport coordinates.
MouseEvent.clientY
Read only-
The Y coordinate of the mouse pointer in viewport coordinates.
MouseEvent.ctrlKey
Read only-
Returns
true
if the control key was down when the mouse event was fired. MouseEvent.layerX
Non-standard Read only-
Returns the horizontal coordinate of the event relative to the current layer.
MouseEvent.layerY
Non-standard Read only-
Returns the vertical coordinate of the event relative to the current layer.
MouseEvent.metaKey
Read only-
Returns
true
if the meta key was down when the mouse event was fired. MouseEvent.movementX
Read only-
The X coordinate of the mouse pointer relative to the position of the last
mousemove
event. MouseEvent.movementY
Read only-
The Y coordinate of the mouse pointer relative to the position of the last
mousemove
event. MouseEvent.offsetX
Read only-
The X coordinate of the mouse pointer relative to the position of the padding edge of the target node.
MouseEvent.offsetY
Read only-
The Y coordinate of the mouse pointer relative to the position of the padding edge of the target node.
MouseEvent.pageX
Read only-
The X coordinate of the mouse pointer relative to the whole document.
MouseEvent.pageY
Read only-
The Y coordinate of the mouse pointer relative to the whole document.
-
The secondary target for the event, if there is one.
MouseEvent.screenX
Read only-
The X coordinate of the mouse pointer in screen coordinates.
MouseEvent.screenY
Read only-
The Y coordinate of the mouse pointer in screen coordinates.
MouseEvent.shiftKey
Read only-
Returns
true
if the shift key was down when the mouse event was fired. MouseEvent.mozInputSource
Non-standard Read only-
The type of device that generated the event (one of the
MOZ_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.webkitForce
Non-standard Read only-
The amount of pressure applied when clicking.
MouseEvent.x
Read only-
Alias for
MouseEvent.clientX
. MouseEvent.y
Read only-
Alias for
MouseEvent.clientY
.
Usage notes
Behavior of mouseenter
events
One
mouseenter
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 of mouseover
events
A single
mouseover
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 of mouseenter
events sent can be quite huge and cause significant performance problems. In such cases, it is better to listen for mouseover
events.
Combined with the corresponding mouseleave
(which is fired at the element when the mouse exits its content area), the mouseenter
event acts in a very similar way to the CSS :hover
pseudo-class.
Examples
The mouseover
documentation has an example illustrating the difference between mouseover
and mouseenter
.
mouseenter
The following trivial example uses the mouseenter
event to change the border on the div
when the mouse enters the space allotted to it. It then adds an item to the list with the number of the mouseenter
or mouseleave
event.
HTML
<div id="mouseTarget">
<ul id="unorderedList">
<li>No events yet!</li>
</ul>
</div>
CSS
Styling the div
to make it more visible.
#mouseTarget {
box-sizing: border-box;
width: 15rem;
border: 1px solid #333;
}
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 #333";
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
Specification |
---|
UI Events # event-type-mouseenter |
HTML Standard # handler-onmouseenter |
Browser compatibility
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