MouseEvent: screenX property

{{APIRef("Pointer Events")}}

The screenX read-only property of the {{domxref("MouseEvent")}} interface provides the horizontal coordinate (offset) of the mouse pointer in screen coordinates.

[!NOTE] In a multiscreen environment, screens aligned horizontally will be treated as a single device, and so the range of the screenX value will increase to the combined width of the screens.

Value

A double floating point value in pixels.

Early versions of the spec defined this as an integer referring to the number of pixels.

Examples

This example displays your mouse's coordinates whenever you trigger the {{domxref("Element/mousemove_event", "mousemove")}} event.

HTML

<p>Move your mouse to see its position.</p>
<p id="screen-log"></p>

JavaScript

let screenLog = document.querySelector("#screen-log");
document.addEventListener("mousemove", logKey);

function logKey(e) {
  screenLog.innerText = `
    Screen X/Y: ${e.screenX}, ${e.screenY}
    Client X/Y: ${e.clientX}, ${e.clientY}`;
}

Result

{{EmbedLiveSample("Examples")}}

Routing an event

When you trap events on the window, document, or other roomy elements, you can get the coordinates of that event (e.g., a click) and route it properly, as the following example demonstrates:

function checkClickMap(e) {
  if (e.screenX < 50) doRedButton();
  if (50 <= e.screenX && e.screenX < 100) doYellowButton();
  if (e.screenX >= 100) doRedButton();
}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{ domxref("MouseEvent") }}
• {{ domxref("MouseEvent.screenY","screenY") }}
• {{ domxref("MouseEvent.clientX","clientX") }} / {{ domxref("MouseEvent.clientY", "clientY") }}
• Coordinate systems