The clientX read-only property of the MouseEvent interface provides the horizontal coordinate within the application's viewport at which the event occurred (as opposed to the coordinate within the page).

For example, clicking on the left edge of the viewport will always result in a mouse event with a clientX value of 0, regardless of whether the page is scrolled horizontally.


var x = instanceOfMouseEvent.clientX

Return value

A double floating point value, as redefined by the CSSOM View Module. Originally, this property was defined as a long integer. See the "Browser compatibility" section for details.


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


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


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}`;



Browser compatibility

BCD tables only load in the browser

See also