Javascript

I am client side, I am something akin to GUI and even though you claim you don't know me, you have seen my face, it is all the faces you thought you knew, it is the front end, they smile, they talk, they hear, an event listener is triggered and something happens I know, I can't tell what is going on behind those faces even though I can make you laugh, have you cry, sob, or be very happy because I excel in colors, in party tricks, I am the joker of the town, charasmatic and cool, underneath it all, I am just a front with no face.