Wheel diagnostics
Mouse scroll test
See the wheel events your browser receives and look for isolated direction changes that are worth repeating.
How to run it: Start the test, keep the pointer inside the test area, and scroll up and down for 10 seconds.
Connect a mouse or trackpad with wheel input to run this test. A touch-only screen cannot provide wheel events, so no input will not be reported as a failure.
Ready
Start the test, then scroll up and down inside this area.
- Events
- 0
- Last direction
- —
- Reversals
- 0
- Delta mode
- —
Start the test to record browser wheel events. Raw samples stay in this page’s memory.
Interpretation
How to test if mouse scroll is working
Use this mouse scroll test by moving the wheel steadily in one direction, then the other. A consistent result means the recorded session did not contain an isolated reverse event that matched this test’s heuristic; a possible inconsistency means several short reverse events appeared inside otherwise steady input.
Intentional changes from scrolling down to scrolling up count as normal direction reversals. This scrolling mouse test separates those transitions from brief down–up–down or up–down–up patterns that may be worth repeating.
Limitations
What a mouse scroll wheel tester cannot prove
A browser receives processed wheel events, not direct measurements from the physical encoder. Operating-system acceleration, trackpads, browser behavior, and device software can change event timing and magnitude.
This mouse scroll wheel test checks wheel movement, not the wheel’s middle-button click. Use the result as an observation: repeat it, try another browser, and compare another mouse before replacing hardware.
How it works
How this mouse scroll tester reads wheel input
This mouse scroll tester records each WheelEvent with a high-resolution timestamp, horizontal and vertical delta, and deltaMode. That includes horizontal input when the browser reports it, while capped local samples keep repeated sessions responsive.
An isolated reversal is highlighted only when a short opposite-direction event quickly returns to the previous direction. That rule is deterministic, but it remains a heuristic rather than a hardware diagnosis.
Continue diagnosing
Related mouse tests
Useful answers
Mouse wheel questions
How do I test if my mouse scroll is working?
Start the test, keep your pointer in the test area, and move the wheel steadily up and down. A consistent session shows that your browser received wheel input; repeat the same motion if you notice a jump or a missed scroll.
Why does my mouse wheel jump the wrong way?
An isolated reverse event can come from the wheel mechanism, operating-system settings, browser behavior, or an intentional direction change. Repeat this mouse scrolling test and compare another browser or mouse before drawing a conclusion.
Are wheel delta values pixels?
Not always. The browser reports a delta mode with each event: pixels, lines, or pages. This test records and labels that mode instead of treating every value as physical distance.
Can I test horizontal mouse scroll?
Yes. The tool records horizontal as well as vertical wheel input when your mouse, trackpad, or operating system exposes it to the browser. A tilt wheel or modified scroll gesture may behave differently between applications.
Does this test the scroll-wheel button click?
No. This page is a mouse scroll wheel test for movement. Pressing the wheel is usually a middle-button action, so use the Mouse Button Test to check whether that click reaches your browser.
Does a flagged reversal prove an encoder failure?
No. The flag is a browser-level heuristic for a short opposite-direction event inside a directional run. It cannot prove which physical or software layer caused it.