MouseEvent.screenX

The screenX read-only property of the MouseEvent interface provides the horizontal coordinate (offset) of the mouse pointer in global (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.

Syntax

var x = instanceOfMouseEvent.screenX

Return value

A double floating point value.

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

Example

This example displays your mouse's coordinates whenever you trigger the 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

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

Specification
UI Events
# dom-mouseevent-screenx

Browser compatibility

BCD tables only load in the browser

See also