In JavaScript, the Firefox-only, obsolete MozMousePixelScroll event fires asynchronously when a mouse wheel or similar device is operated (MDN). Prefer the standard wheel event.
Register a listener with addEventListener. Check readiness and browser support before you rely on this event.
Syntax
Listen for MozMousePixelScroll. Start with this line.
JavaScript
addEventListener("MozMousePixelScroll", fn)
Call
What it does
addEventListener("MozMousePixelScroll", fn)
Primary signature.
Built into the browser. Listen with el.addEventListener("MozMousePixelScroll", …) — no import required.
Library declarations
JavaScript
addEventListener("MozMousePixelScroll", fn)
Parameters
Parameter
Description
Handler prop
Optional. onMozMousePixelScroll
Return Value
Return Value
Description
*
Fires as an Element event (listener receives the Event object).
JavaScript Examples
Example 1 — Legacy MozMousePixelScroll Log
Study-only: see if the obsolete Firefox event fires in your browser.
Primary path.wheel runs everywhere students build today.
Optional legacy. Moz may also fire in old Firefox — for study only.
Do not depend on Moz. Outside Gecko it stays silent.
Ship only wheel in production code.
Compatibility
Browser Support
ElementMozMousePixelScroll is Deprecated and Non-standard on MDN (Firefox/Gecko history). Do not add it to new code — migrate to wheel.
✓ Deprecated · Non-standard
Element MozMousePixelScroll
Obsolete Firefox-only wheel event. Prefer the standard wheel event with deltaX / deltaY.
LegacyDeprecated
Google ChromeSupported · Desktop & Mobile
Full support
Mozilla FirefoxSupported · Desktop & Mobile
Full support
Apple SafariSupported · macOS & iOS
Full support
Microsoft EdgeSupported · Chromium
Full support
Internet ExplorerNo native support · Use a polyfill
Polyfill
OperaSupported · Modern versions
Full support
Samsung InternetSupported · Android
Full support
Android WebViewSupported · Modern WebView
Full support
MozMousePixelScrollAvoid
Bottom line: Historical Firefox only. Use wheel for portable apps.
Frequently Asked Questions
It is a Firefox-only, obsolete, non-standard event fired asynchronously when a mouse wheel or similar device is operated. MDN marks it Deprecated and Non-standard. Prefer the standard wheel event.
No. Use addEventListener("wheel", …) with WheelEvent.deltaX / deltaY / deltaMode. MozMousePixelScroll was never a portable web standard.
Both are legacy Gecko scroll events. DOMMouseScroll was oriented around line/page accumulation; MozMousePixelScroll was Gecko’s finer pixel-oriented companion. Neither should be used in new code.
Per MDN: negative detail means scrolling toward the bottom or right; positive means toward the top or left. Trusted events never use detail 0. Prefer wheel’s deltaY / deltaX instead.
Historically Firefox (Gecko) only. Chrome, Safari, Edge, and other engines do not implement this Mozilla-prefixed event.
MDN lists WheelEvent (inherits from MouseEvent, UIEvent, and Event). Older docs also mention the MouseScrollEvent interface name.