Mouse Tester

Position, buttons and wheel

Position shows the pointer's coordinates inside the test area, following that pair of numbers while you draw a slow stroke reveals whether tracking is continuous or jumps. Buttons shows which are pressed: Pointer Events expose left, right, middle (the wheel), and the two side navigation buttons (back/forward), when they exist.

Wheel accumulates scroll from deltaY, the value the browser delivers on each turn. That value has no universal physical unit: it depends on the mouse, the system and the scroll settings, so it is for confirming scroll direction and continuity, not for measuring millimeters of rotation.

• Position: pointer coordinates in the area.
• Buttons: left, right, middle and side buttons.
• Clicks: a count to catch unwanted double clicks.
• Wheel: accumulated deltaY (direction and continuity).

Phantom double click and a dead button

Example 1, a mouse that "clicks twice on its own": make one deliberate left click and watch the click count. If a single intentional click registers as two events, the micro-switch has chatter (worn contacts), a common defect that ruins dragging files and selecting text.

Example 2, a side button that does nothing in the browser: press the mouse's back/forward buttons. If they do not light up here, either the mouse does not expose them or the driver has not mapped them, in which case the manufacturer's software usually fixes it by reassigning the function.

When to use it and what the symptoms mean

Use it when buying a used mouse, after cleaning the sensor, when you suspect worn buttons after years of use, or to separate a hardware fault from a system setting (speed, acceleration, surface). It is also a quick check that a freshly connected mouse works on every button.

How to read it: jumps in position during a smooth move suggest a dirty sensor, a reflective mousepad or an unstable polling rate; double clicks from a single click indicate a worn switch; a button that never lights points to a physical fault. Note that measuring real DPI is not possible here, DPI is a property of the sensor, not a browser event.

• Jumps in position: dirty sensor, poor surface or unstable rate.
• One click becomes two: micro-switch chatter.
• Button that never lights: physical fault or driver.
• DPI: not measurable here, it is a sensor property.