MouseEvent: movementX property
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
The movementX read-only property of the MouseEvent interface provides the difference in the X coordinate of the mouse (or pointer) between the given move event and the previous move event of the same type.
In other words, the value of the property is computed like this: currentEvent.movementX = currentEvent.screenX - previousEvent.screenX.
The value is zero for all events other than mousemove, pointermove, and pointerrawupdate.
Warning:
Browsers use different units for movementX and screenX than what the specification defines.
Depending on the browser and operating system, the movementX units may be a physical pixel, a logical pixel, or a CSS pixel. You may want to avoid the movement properties, and instead calculate the delta between the current client values (screenX, screenY) and the previous client values.
Value
A number.
Always zero on any MouseEvent other than mousemove, and any PointerEvent other than pointermove or pointerrawevent.
Examples
Log mouse movement for mousemove events
This example logs the amount of mouse movement using movementX and movementY.
HTML
<p id="log">Move your mouse around.</p>
JavaScript
const log = document.getElementById("log");
function logMovement(event) {
log.insertAdjacentHTML(
"afterbegin",
`movement: ${event.movementX}, ${event.movementY}<br>`,
);
while (log.childNodes.length > 128) log.lastChild.remove();
}
document.addEventListener("mousemove", logMovement);
Result
Specifications
| Specification |
|---|
| Pointer Lock 2.0 # dom-mouseevent-movementx |