Prepare a clean input environment
Input methods, macro tools, device utilities, and remote-control software can alter events. Save work, close unnecessary tools, and click the test area once.
For wireless devices, check battery and receiver distance. For wired devices, compare a direct connection to another USB port instead of a hub.
Check missing and duplicate keys
Press every key in sequence and confirm that the on-screen keyboard responds immediately. If one physical press rapidly creates multiple events, investigate chatter or repeat settings.
Fn combinations and brightness or volume keys may be handled by the operating system or vendor software before the browser sees them.
- Missing event: compare key, port, and driver
- Duplicate event: check repeat and switch chatter
- Special keys may not reach the browser
Check mouse buttons and wheel
Test left, right, and middle buttons separately, then scroll both directions and inspect the accumulated response.
For unintended double-clicks, adjust the operating system's double-click speed and retest. A browser cannot precisely measure sensor tracking or true DPI.
Cross-check another environment
Try another USB port and browser, then another computer when possible. A problem on only one computer points more strongly to drivers, utilities, or accessibility settings.
The same failed key or button across environments makes hardware trouble more likely. Check warranty terms before opening or repairing the device.