MouseEvent: movementX property
Baseline 2023Newly available
Since September 2023, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.
The movementX read-only property of the MouseEvent interface provides the difference in the X coordinate of the mouse pointer between the given event and the previous mousemove event.
In other words, the value of the property is computed like this: currentEvent.movementX = currentEvent.screenX - previousEvent.screenX.
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.
Examples
This example logs the amount of mouse movement using movementX and movementY.
HTML
<p id="log">Move your mouse around.</p>
JavaScript
function logMovement(event) {
log.insertAdjacentHTML(
"afterbegin",
`movement: ${event.movementX}, ${event.movementY}<br>`,
);
while (log.childNodes.length > 128) log.lastChild.remove();
}
const log = document.getElementById("log");
document.addEventListener("mousemove", logMovement);
Result
Specifications
| Specification |
|---|
| Pointer Lock 2.0 # dom-mouseevent-movementx |