Is there some low level checking by the js engine to see if it should stop processing the function if there is no return? Or, to put it another way, does addin

Is there some low level checking by the js engine to see if it should stop processing the function if there is no return? Or, to put it another way, does adding the return explicitly tell the engine, "ok we're done here", as opposed to a small amount of processing required by the engine to determine that for itself?