Are Glasses/Mask part of the body?
 

If a player knocks the opposing player's Spectacles/Sport Glasses, or face Mask is it considered a contact or such accessories are not considered part of the player's body & thus hitting them in any way won't result in foul. I guess it's abit different from pulling player's jersey/pants.

I don't see it as any different from a rules standpoint. If the contact causes an advantage (or a disadvantage), then it's a foul. It's more likely that knocking the glasses would cause an advantage than knocking the jersey.