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MouseEvent.clientX

The clientX read-only property of the MouseEvent interface provides the horizontal coordinate within the application's client area at which the event occurred (as opposed to the coordinates within the page). For example, clicking in the top-left corner of the client area will always result in a mouse event with a clientX value of 0, regardless of whether the page is scrolled horizontally. Originally, this property was defined as a long integer. The CSSOM View Module redefined it as a double float. See the Browser compatibility section for details.

Syntax

var x = instanceOfMouseEvent.clientX

Return value

A number

Example

<!DOCTYPE html> 
<html>
  <head>
    <title>clientX/clientY example</title>

    <script>
      function showCoords(evt){
        alert(
          "clientX value: " + evt.clientX + "\n" +
          "clientY value: " + evt.clientY + "\n"
        );
      }
    </script>
  </head>
  <body onmousedown="showCoords(event)">
    <p>To display the mouse coordinates click anywhere on the page.</p>
  </body>
</html>

Specifications

Specification	Status	Comment
CSS Object Model (CSSOM) View Module The definition of 'clientX' in that specification.	Working Draft	Redefines `MouseEvent` from `long` to `double`.
Document Object Model (DOM) Level 3 Events Specification The definition of 'MouseEvent.clientX' in that specification.	Obsolete	No change from Document Object Model (DOM) Level 2 Events Specification.
Document Object Model (DOM) Level 2 Events Specification The definition of 'MouseEvent.clientX' in that specification.	Obsolete	Initial definition.

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	Yes	Yes	Yes	6	Yes	Yes
Value type changed from `long` to `double`	56	?	?	?	?	?