All That David Copperfield Kind of ...

I think what it means is that Salinger isn't going to talk about his life in the past and isn't going to go into the autobiographical  aspects of his life but tell you how and where he is at that moment. Although Catcher in the Rye is quite straight forward with the moments that occur the author also has to talk slightly about his past, but he never tells his entire life story like David Copperfild.