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Ubify Core Engineering Team
SOFTWARE ENGINEERS & SYSTEMS ARCHITECTS
About This Tool
The Keyboard Key Rollover Tester tests your physical keyboard matrix to detect simultaneous keystroke limits (2KRO, 6KRO, or full NKRO) and inspect raw DOM key codes.
### Why Key Rollover and Ghosting Matter Membrane and budget keyboards wire switches across an intersecting electrical grid matrix. When several keys on shared matrix rows and columns are pressed at once, electrical ambiguity can prevent additional keys from registering (ghosting / blocking): - **2-Key Rollover (2KRO)**: Common on standard office keyboards; pressing combinations like 'W + Shift + Space' during gaming can block the jump action. - **6-Key Rollover (6KRO)**: Standard USB HID limit allowing up to 6 simultaneous alphanumeric keys plus modifiers. - **N-Key Rollover (NKRO)**: High-performance mechanical and gaming keyboards with isolated diodes per switch allowing every pressed key to register simultaneously without blocking. - **Event Telemetry**: Displays 'event.key' (character value), 'event.code' (physical key position such as 'KeyW' or 'Space'), and legacy 'event.which' numeric codes.
### Worked Diagnostic Example 1. Focus the tester and hold down 'W', 'A', and 'Left Shift'. 2. While holding those keys, tap 'Space' or 'R'. 3. If all keys appear active in the pressed list simultaneously, your keyboard matrix successfully registers multi-key combinations. 4. If 'Space' fails to register while the other three keys are depressed, your keyboard matrix exhibits ghosting blocking on that electrical cluster.
### Client-Side Hardware Inspection Keystroke interception and diagnostic telemetry listen to native browser window events (keydown and keyup). No keystroke logs, passwords, or typing history are transmitted over the network or saved to storage.
How to Use
- 1
Click anywhere inside the testing area to ensure the browser window has active focus.
- 2
Press individual keys or multiple simultaneous key combinations across your keyboard.
- 3
Check the active key list to confirm every pressed key registers without dropped inputs.
- 4
Inspect the event.key, event.code, and numeric which values, or click Reset Keys to clear the state.
Frequently Asked Questions
What is the difference between event.key and event.code?
event.code identifies the physical switch location on your keyboard hardware (e.g., "KeyA"), while event.key reflects the generated character influenced by Shift, CapsLock, and keyboard language layouts.
Why do browser shortcut keys like Ctrl+W or F11 trigger browser actions?
Certain operating system and browser system-level shortcuts intercept hardware inputs before web page event handlers can consume or prevent them.
Are any keystrokes sent to external servers?
No. All key event listeners run purely in your local browser session with zero network transmission.