The MouseEvent.button
read-only property indicates which button was pressed on the mouse to trigger the event.
This property only guarantees to indicate which buttons are pressed during events caused by pressing or releasing one or multiple buttons. As such, it is not reliable for events such as mouseenter
, mouseleave
, mouseover
, mouseout
or mousemove
.
Users may change the configuration of buttons on their pointing device so that if an event's button property is zero, it may not have been caused by the button that is physically left–most on the pointing device; however, it should behave as if the left button was clicked in the standard button layout.
Note: Do not confuse this property with the MouseEvent.buttons
property, which indicates which buttons are pressed for all mouse events types.
Syntax
var buttonPressed = instanceOfMouseEvent.button
Return value
A number representing a given button:
0
: Main button pressed, usually the left button or the un-initialized state1
: Auxiliary button pressed, usually the wheel button or the middle button (if present)2
: Secondary button pressed, usually the right button3
: Fourth button, typically the Browser Back button4
: Fifth button, typically the Browser Forward button
As noted above, buttons may be configured differently to the standard "left to right" layout. A mouse configured for left-handed use may have the button actions reversed. Some pointing devices only have one button and use keyboard or other input mechanisms to indicate main, secondary, auxilary, etc. Others may have many buttons mapped to different functions and button values.
Example
HTML
<button id="button" oncontextmenu="event.preventDefault();">Click here with your mouse...</button> <p id="log"></p>
JavaScript
let button = document.querySelector('#button'); let log = document.querySelector('#log'); button.addEventListener('mouseup', logMouseButton); function logMouseButton(e) { if (typeof e === 'object') { switch (e.button) { case 0: log.textContent = 'Left button clicked.'; break; case 1: log.textContent = 'Middle button clicked.'; break; case 2: log.textContent = 'Right button clicked.'; break; default: log.textContent = `Unknown button code: ${e.button}`; } } }
Result
Specifications
Specification | Status | Comment |
---|---|---|
Document Object Model (DOM) Level 3 Events Specification The definition of 'MouseEvent.button' in that specification. |
Obsolete | Compared to Document Object Model (DOM) Level 2 Events Specification, the return value can be negative. |
Document Object Model (DOM) Level 2 Events Specification The definition of 'MouseEvent.button' in that specification. |
Obsolete | Initial definition. |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
button | Chrome Full support 1 | Edge Full support 12 | Firefox Full support 1 | IE Full support 9 | Opera Full support 10.6 | Safari Full support 3.1 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android Full support 4 | Opera Android Full support 11 | Safari iOS Full support 2 | Samsung Internet Android Full support 1.0 |
Legend
- Full support
- Full support