Input tests
KeyboardEvent provides key, code, location, repeat and modifier state. Pointer Events combine mouse, pen and touch information. These are events delivered by the operating system and browser; missing input can occur before the page sees it.
Camera and microphone
MediaDevices.getUserMedia requests a live stream only after a user action on HTTPS. Video dimensions come from the active stream. AnalyserNode provides uncalibrated waveform and frequency samples. Media tracks are stopped when the test ends.
Display timing and dimensions
Screen and viewport properties use CSS pixels. Estimated physical pixels multiply CSS dimensions by devicePixelRatio and are labeled estimates. requestAnimationFrame timing approximates refresh behavior while the visible tab is active.
Controllers and touch
The Gamepad API exposes mapped buttons and axes after activation. Pointer events provide browser contacts and optional pressure. Mapping, vibration and reserved system gestures differ by browser and hardware.
Repeatability
Run a test several times under the same conditions, then compare another current browser, cable, port or computer where practical. A consistent observation is better support evidence, but it is still not laboratory certification.