Mouse Input & Pointer Inspector
A real-time diagnostic utility inspecting live PointerEvent telemetry and demonstrating the security boundaries between browser DOM events and hardware firmware.
Live PointerEvent Stream
2. What Can a Website Actually See From a Mouse?
Web browsers receive high-level event messages dispatching through the operating system's window manager. The browser is informed where the pointer moved in viewport pixels, but is deliberately restricted from querying low-level hardware registers.
3. Browser DOM Events vs Hardware Firmware
| Property Category | Browser Accessible? (Web Standards) | How It Is Retrieved |
|---|---|---|
| Client Coordinates (X, Y) | Yes (100% Accessible) | PointerEvent clientX / clientY within viewport |
| Movement Deltas (dx, dy) | Yes (100% Accessible) | PointerEvent movementX / movementY increments |
| Button Click Mask | Yes (100% Accessible) | PointerEvent buttons bitmask (1, 2, 4, 8, 16) |
| Device Pixel Ratio | Yes (100% Accessible) | window.devicePixelRatio (OS display scaling) |
| Raw Hardware DPI | No (Inaccessible in Sandbox) | Not exposed by any browser security standard |
| USB Polling Rate (Hz) | No (Estimated only) | Hardware report frequency hidden by OS event loop |
| Onboard Mouse Memory | No (Inaccessible in Sandbox) | Requires WebHID / WebUSB with explicit user grant |
Mouse Input Test FAQ
Common questions about browser mouse input APIs and security.
Why can websites see my cursor position but not my DPI?
Can WebHID read mouse DPI?
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