Combination coverage
- Complete a test to compare target, matched, missing, and extra keys.
Compare target, matched, missing, and extra-key counts with both text and numbers, not color alone.
Hotkey and Combination Tester
Choose a shortcut combination and press it in the capture area to see whether this browser receives every target key, left/right modifier, and extra key.
Test settings
Separate codes with plus signs; up to 8 keys and at least one ordinary key.
Enter a valid combination of distinct KeyboardEvent.code values.
Round target—
—Press the full combination and release it. Tab remains available to leave the capture area.
- Target keys
- —
- Currently held
- 0
- Seen this round
- 0
- Elapsed
- 0.0 s
Keys currently held
- —
Event order
- —
Choose a combination and start a test.
Capture status—No valid test has been completed
- Target keys
- —
- Best snapshot
- —
- Missing keys
- —
- Extra keys
- —
The result describes only keyboard events received by this page; reserved system shortcuts may never enter the browser.
Target keys—
Best snapshot—
Target combination and keys held together
Learn more
Method and result definition
The tool saves the held-code snapshot after each non-repeat keydown and keeps the one with the most target matches and fewest extra keys. It reports a complete capture only when all targets are present and extras are zero.
Combination time uses the unrounded monotonic clock internally and displays milliseconds; pass/fail logic never uses the rounded value.
Coverage includes complete, missing, extra, left/right modifiers, repeats, composed input, Tab navigation, timeout, focus loss, copy, and reset.
Limits and system interception
Alt-Tab, Command-Tab, Ctrl-Alt-Delete, Command-Space, and browser shortcuts may be handled first. A webpage cannot inspect global shortcut registrations in other applications or prove hardware rollover.
How do I test a keyboard shortcut?
Choose a system mode and preset, or enter KeyboardEvent.code values separated by plus signs. Start a round, press the whole combination, and release it.
Why does Command-Space not register?
macOS commonly handles Command-Space for input-source switching or search before the browser sees it. A missing event does not prove a damaged key.
How can I tell left and right Shift apart?
Use ShiftLeft and ShiftRight. The tool also keeps KeyboardEvent.location so the two modifier positions remain distinct.
Tool information and sources
All key events and results stay in this browser's memory. Nothing is uploaded, put in the URL, saved to local storage, or sent to a runtime API.
No third-party runtime code or assets are reused. The algorithm and interface are independently implemented; external links explain browser event standards only.