Detect touchpad vs mouse in Javascript

Is there any way to detect if the client is using a touchpad vs. a mouse with Javascript?

Or at least to get some reasonable estimate of the number of users that use touchpads as opposed to mice?

Answer

In the general case, there is no way to do what you want. ActiveX might allow you to see and examine USB devices, but in the best case, even if that is somehow possible, that limits you to IE users. Beyond that, there is no way to know.

You might be able to discern patterns in how (or how often) a touchpad user moves the cursor versus how a mouse user might move the cursor. Differentiating between physical input devices in this way is an absurdly difficult prospect, and may be wholly impossible, so I include here it for completeness only.