Output
Wheel events; signed deltas; reversals
UserBenchmark / All Tools / Scroll Wheel Jump Test
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Scroll Wheel Jump Test
Track unexpected direction reversals during a one-direction scroll.
Free to useNo downloadNo sign-up
Scroll Wheel Jump Test · At a glance
Quick answer: Track unexpected direction reversals during a one-direction scroll. A reversal is an opposite-signed wheel event.
Scroll Wheel Jump Test
The test loads when you open it. Device access is requested only after you choose to start.
Detailed guide
How to use this tool
- Scroll slowly in one direction without reversing your finger.
- Look for sign changes, then reset and repeat in the opposite direction.
Input
One-direction wheel movement
Browser requirement
WheelEvent.deltaMode and delta values
Processing
Runs on your device; no tool-result upload
How it works and what the result means
A reversal means the sign of the browser wheel delta changed. Delta units may be pixels, lines or pages depending on the device and browser.
Reading the result
A reversal is an opposite-signed wheel event. Repeated reversals during deliberate one-way wheel movement are more informative than a single event.
What to check next
Momentum trackpads can reverse naturally. Compare a physical wheel in another application before concluding that the encoder is faulty.
Trackpads and momentum scrolling can naturally reverse or continue after you stop. Compare with a physical wheel before diagnosing a faulty encoder.
Frequently asked questions
Does this count missed wheel notches?
It sees delivered events, not the mechanical wheel. You need a known physical movement count to investigate missing notches.
How do I start the Scroll Wheel Jump Test?
Move the wheel in one direction inside the test area. Check the count, direction and reversal log; reset before trying the other direction.
Does this tool require a download or an account?
No. Open the interactive tool above in a modern browser. The instructions and explanations are available even with JavaScript disabled; running a test needs JavaScript.
Why can two attempts give different results?
Power settings, background tasks, browser scheduling, operating-system input processing and device settings affect measurements. Compare repeated attempts with identical settings rather than the single highest score.