Four separate checks, not one
Each button tile above turns solid on the way down and keeps a green outline once it has fired, confirming that specific switch sends a signal at all; right-click is captured here as a fifth button test rather than opening the usual context menu, since that menu would just get in the way of the test. The other three checks run independently of the buttons: the timing gap between two left clicks, whether the wheel produces a tick for each direction, and roughly how often the sensor reports its position while moving.
None of that catches a switch failing in a noisier way than total silence. Contact bounce, where a worn switch fires two rapid signals from one physical press, produces a timing gap that looks exactly like a real fast double-click in the log, so there's no way to tell the two apart from the reading alone. A sensor that has started skipping or jittering mid-movement similarly won't show up as a clean pass/fail here, the way a switch that never registers at all does.
Double-click timing and what the number means
Every time the left button is pressed twice, this tool measures the gap between the two presses and checks it against Windows' own double-click window. That window is a real operating-system setting (the registry value behind it is literally named DoubleClickSpeed), not a browser guess: Microsoft's .NET documentation defines it as "the maximum number of milliseconds that may elapse between a first click and a second click for the OS to consider the mouse action a double-click," and community guides to that same control consistently report an out-of-the-box default of 500 ms with an adjustable range of roughly 200 to 900 ms.
A gap that lands well inside that range on an unmodified system would register as a double-click; a gap past the slowest end of the range (900 ms) would register as two separate single clicks, regardless of intent. macOS handles the same idea differently. Apple's Accessibility settings expose it as a relative slider (System Settings > Accessibility > Pointer Control > Double-click speed), with no single documented millisecond default to compare against on that platform.
Estimating report rate, and why the number has an asterisk
A mouse doesn't send a continuous stream of position data; it reports its position at a fixed interval over USB, and that interval is the polling rate (also called report rate), typically 125 Hz (one report every 8 ms) on ordinary mice and 500-1000+ Hz on mice marketed for gaming. This tool estimates that rate from the timing between movement events while the pointer is inside the test area.
The asterisk: Chromium and Firefox both batch, or coalesce, continuous pointer-movement events and only hand them to page JavaScript right before the next screen refresh, a documented performance optimization (a typical mouse can report movement roughly 100 times a second while a typical display refreshes only 60 times a second, so batching avoids redundant work). Those two browsers expose a way around it, the PointerEvent.getCoalescedEvents() method, which recovers the individual pre-batching samples and is what this tool uses automatically when available. That method only reached Safari in version 18.2 (December 2024), so a copy of Safari older than that caps this reading near the display's refresh rate, not the mouse's true hardware rate. The tool labels which method it used so that distinction isn't hidden.
Worked examples
Two clicks land 340 ms apart: that's past the 500 ms default but still inside the 200-900 ms adjustable range, so it would only register as a double-click if that Windows setting had been loosened from its out-of-the-box value toward the slow end.
The report-rate reading in Chrome settles around 125 Hz on an ordinary office mouse: that matches an 8 ms interval between reports, consistent with the industry-standard 125 Hz baseline most non-gaming mice ship with.
The same test in a pre-18.2 copy of Safari shows a reading that won't climb past roughly 60-144 Hz even on a mouse known to support 1000 Hz: that's the display-refresh ceiling described above, not a fault with the mouse.