I tried my PS2 Dual Shock connected via a GAME usb adapter.
Chrome: No go.
Firefox:
c12-5-PS Vibration Feedback Converter
Button 0: Triangle (Windows recognizes as Button 1)
Button 1: Circle (Windows recognizes as Button 2)
Button 2: X (Windows recognizes as Button 3)
Button 3: Square (Windows recognizes as Button 4)
Button 4: L2 (Windows recognizes as Button 5)
Button 5: R2 (Windows recognizes as Button 6)
Button 6: L1 (Windows recognizes as Button 7)
Button 7: R1 (Windows recognizes as Button 8)
Button 8: Select (Windows recognizes as Button 9)
Button 9: L3 (Windows recognizes as Button 10)
Button 10: R3 (Windows recognizes as Button 11)
Button 11: Start (Windows recognizes as Button 12)
Axis 0: Left Stick (Left: -100 Right: 100) / D-Pad Left: -100 Right: 100 with analog off.
Axis 1: Left Stick (Up: -100 Down: 100) / D-Pad Up: -100 Down: 100 with analog off.
Axis 2: Right Stick (Up: -100 Down: 100)
Axis 3: Not used
Axis 4: D-Pad Left: -100 Right: 100 with analog on-
Axis 5: Right Stick (Left: -100 Right: 100) / D-Pad Up: -100 Down: 100 with analog on.