Key Event Tester

What is this tool?

Every key you press becomes a KeyboardEvent object, and this page shows you that object as it happens. It is the tool to reach for when you are writing a shortcut handler and need to know exactly what the browser is handing you.

The panel breaks each event into its useful fields: event.key (the character or name produced), event.code (the physical key, independent of layout), event.location (which of a duplicated pair fired), event.repeat (whether the operating system generated it) and the four modifier flags.

A rolling log sits underneath so you can compare a sequence rather than a single press — useful for chords, dead keys and IME behaviour.

How to use it

1. Give the page focus and press a keyThe inspector fills in immediately. There is no start button; monitoring is the default state.
2. Compare key against codePress the same physical key with a different keyboard layout selected in your operating system. event.code stays the same, event.key changes. That difference is the whole reason to use code for game controls and key for text.
3. Filter to what you are debuggingALL, KEYDOWN, KEYUP, REPEAT and MODS narrow the log. MODS is the fastest way to see whether a chord's modifier flags are set the way you expect.
4. Freeze and copyPAUSE MONITORING stops the stream so a fast chord stays on screen. Copy Event puts the selected event on your clipboard as JSON, ready to paste into a bug report. CLEAR empties the log and RESET SESSION starts over.

What the results mean

event.key vs event.code

On a US layout, pressing the key marked Q gives key: “q” and code: “KeyQ”. On AZERTY the same physical key gives key: “a” and still code: “KeyQ”. Bind gameplay to code; read text from key.

event.location

0 means standard, 1 left, 2 right, 3 numpad. It is how you tell left Shift from right Shift, and how you tell numpad Enter from the main Enter when they share a key value.

event.repeat

True marks an event your operating system generated because the key is being held, not a fresh physical press. Ignore repeats when you are counting presses.

Modifier flags

shiftKey, ctrlKey, altKey and metaKey describe the state at the moment of the event. A chord that fails usually fails because one of these is false when your handler assumed it was true.

What it can detect

• The exact key, code, keyCode, location and modifier state of any press
• Whether an event came from your finger or from operating-system auto-repeat
• Layout-dependent differences between key and code
• Left and right variants of duplicated keys, and numpad versus main-block keys

Limits worth knowing

A browser can only report what the platform gives it. These are the honest boundaries of this page, so a result is never read as more than it is.

• This tool does not measure hardware latency, and its own FAQ says as much. Event timestamps include operating-system and browser scheduling, so they describe when the browser saw the key — not how fast the switch or the cable is.
• Shortcuts the browser or operating system claims first — Ctrl+W, Alt+Tab, Cmd+Q and similar — never reach the page and so cannot be inspected here.
• The Fn key on most laptops is resolved inside the keyboard controller and never becomes a browser event.

Tips

• When you write a shortcut handler, check the modifier flags rather than watching for the modifier's own keydown. The flags are set on the event you actually care about.
• Use PAUSE MONITORING before reading a fast chord; otherwise the keyup events push the interesting frame off the top.
• If you need press timing rather than press identity, the Key Press Test measures hold duration and press-to-press intervals.

Troubleshooting

Related documentation

• KeyboardOnline Keyboard TestThe keyboard tester on the home page — press keys, watch them light up.
• KeyboardKey Press TestTimes each press: how long you held it, and how long since the last one.
• KeyboardHID Keyboard TesterBrowser key events side by side with raw WebHID reports, when your browser supports it.
• KeyboardBroken Key DetectorA guided pass over every physical key, plus a consistency re-test for the ones that look wrong.
• KeyboardKeybind CheckerMaps your binds on a visual keyboard and names what could go wrong — without scoring you.