Keyboard & Pointer Event Tester

How to test keyboard and pointer events

1. Focus the test area and press/release keys or combine modifiers.
2. Click mouse buttons or use a touch or pen pointer. Movement logging is optional.
3. Review live held states and filter the log. Pause freezes history while live input state can still update.
4. Prepare a JSON snapshot and download it. Clear removes events, live states and the prepared report.

Keys, codes and modifiers

KeyboardEvent.key reflects the interpreted value and keyboard layout. code identifies a physical-key position where available; its name does not guarantee the printed label. Location is standard (0), left (1), right (2) or numpad (3), where reported. Repeat and composing flags are browser-provided. This is not a text editor and does not reconstruct IME composition text.

Keyboard handlers operate only while the pad has focus. Escape records its received event, releases the pad and disables action prevention; its release may happen after focus has left. Blur, hidden page and lost capture clear held states to avoid stuck keys or pointers after missed releases.

Pointer and wheel fields

Pointer Events represent mouse, touch and pen input. Button identifies the changed button; buttons is a bitmask: primary 1, secondary 2, auxiliary 4, back 8, forward 16. Chorded mouse-button changes can arrive as pointermove. Coordinates are CSS pixels relative to the area's outer border. JSON also includes available pressure, tilt, contact size, pointer ID/type and primary flag.

Pressure is browser-reported and can be a fallback rather than measured force. Pointer capture is requested on a press so releases can reach the pad after moving outside. Touch gestures in the area are dedicated to testing; scroll the page outside it.

Movement and wheel log entries are sampled at most once per 50 ms per event type, with live pointer state updating independently. Wheel deltas retain pixel, line or page units from deltaMode; they are not physical distances.

Action prevention and browser limits

Prevention is off by default. When enabled, cancelable events received inside the pad are prevented, which helps inspect Tab, Space, context-menu actions and some shortcuts. Escape always exits. Browser/OS-reserved actions may be intercepted before JavaScript receives them; this tester cannot bypass that behavior.

The origin flag reflects isTrusted, labeled Browser-origin or Synthetic. It does not prove physical input or human activity. Tool-generated reset rows are synthetic. This page reports received events; it does not certify hardware health, polling rate or input latency.

Bounds and privacy

The latest 200 logged events are kept, with a dropped-event count and 50/100/200-row views. Strings are limited to 128 UTF-16 units. Elapsed time uses a monotonic page timer rounded to hundredths of a millisecond; browser timing/sampling limits apply. A paused log does not record events, but live state still works in the focused area.

No events are uploaded or saved in browser storage. Details use literal text. JSON snapshots include retained key values, modifiers and pointer coordinates, so they may contain private input. Later events do not change a prepared snapshot. Clear and page exit revoke its URL and clear the log.

References: MDN KeyboardEvent.code, PointerEvent and isTrusted.

Frequently asked questions

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