MouseEvent.which

Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The MouseEvent.which read-only property indicates which button was pressed on the mouse to trigger the event. The standard alternatives to this property are MouseEvent.button and MouseEvent.buttons.

Syntax

var buttonPressed = instanceOfMouseEvent.which

Return value

A number representing a given button:

  • 0: No button
  • 1: Left button
  • 2: Middle button (if present)
  • 3: Right button

For a mouse configured for left-handed use, the button actions are reversed. In this case, the values are read from right to left.

Specification

This is not part of any specification.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
which
Non-standard
Chrome Full support 1Edge Full support 12Firefox Full support 1
Notes
Full support 1
Notes
Notes On mousemove events, the which property is incorrectly always set to 1.
IE Full support 9Opera Full support 10.6Safari Full support 3.1WebView Android Full support YesChrome Android Full support YesFirefox Android Full support 4
Notes
Full support 4
Notes
Notes On mousemove events, the which property is incorrectly always set to 1.
Opera Android Full support 11Safari iOS Full support YesSamsung Internet Android Full support Yes

Legend

Full support  
Full support
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.
See implementation notes.
See implementation notes.

See also