Some keys never reach the browser because they are caught by the operating system: the Windows or Command key, Print Screen, F12, and the close window shortcuts. If a key is not checked, also try it outside the browser before considering it broken.
How it works
It marks each key you press on a virtual keyboard, so in a couple of minutes you know if one has stopped responding, if it fires on its own, or if it repeats characters. The keys already tested are highlighted and a counter indicates how many are left to go through the entire key.
Listed below is the raw data for each event: the logical character (key), the language-independent physical code (code), the inherited keyCode, the location—left, right, or numeric pad—the active modifiers, and whether the event came from automatic repeat. It's the quick reference when you're programming keyboard shortcuts.
The simultaneous key counter measures the keyboard's rollover: how many keystrokes at a time it is capable of transmitting. Membrane keyboards typically stop at three or four, while one with N-key rollover recognizes as many as you can hold down.
Examples
Shift + 1key: "!" · code: "Digit1"key depends on modifiers and keyboard language; code always identifies the same physical key, and that is why it is the one to use in shortcuts.Ctrl derechocode: "ControlRight" · location: 2Duplicate keys are distinguished by their location, so you can check Shift, Ctrl, or Alt separately on each side.A (mantener pulsada)repeat: trueEvents marked as repeat are generated by the operating system when you hold the key; If they appear without you holding it, the contact of that key is failing.Use cases
- Check a used or newly purchased keyboard before the return period expires.
- Detect keys that repeat themselves or that stopped responding after a liquid spill.
- Find out what code or keyCode value a key emits while programming a shortcut.
- Measure how many simultaneous keys the computer recognizes, something key for games and long combinations.
- Confirm the physical layout of your equipment when the printed labels do not match what you write.
Frequently asked questions
Why is the Windows or Command key not checked?
Because the operating system intercepts it before it reaches the browser: pressing it opens the start menu or the search engine and the page loses focus. The same thing happens with Print Screen and with F12 on some systems. It doesn't mean the key is broken.
What is the difference between key, code and keyCode?
key is the character or name that produces the key and changes with the language and with modifiers. code identifies the physical position on the keyboard and never changes. keyCode is a legacy number, marked as obsolete in the specification: it still works but should not be used in new code.
Why do some keys stop registering when I press several keys?
It is the keyboard rollover limit. Membrane models share circuits between rows and columns, so after three or four simultaneous keys they begin to ignore keystrokes or produce phantom combinations. Mechanical keyboards with N-key rollover do not have that limit.
Why don't the letters displayed on the virtual keyboard match mine?
The drawn keyboard uses the ANSI layout as a base. When the browser exposes the Keyboard API—currently only Chromium on desktop—the labels are replaced with those of your actual layout, so an AZERTY or QWERTZ keyboard displays correctly. ANSI labels are maintained in the rest of the browsers.
Is it for a wireless or notebook keyboard?
Yes. The test works with the events delivered by the system, so it works the same with USB, Bluetooth, wireless keyboards with a receiver or integrated into a notebook. On compact keyboards, keys that only exist with the Fn key appear as additional codes below the keyboard.