Javascript, Best method for creating object with vars

I am creating an object in a function - am passed 3 vars, 1 is a name, 2 is a name, and 3 is an array.

So right now I create this object like so

   createObj(var, var2, var3){
     var temp1 = {};
     var temp2 = {};

     temp2[var2] = var3;
     temp1[var] = temp2;
    }

Which creates and object like

 {var1 : {var2 : var3 }};

So this works just fine (I want the object looking like that), however I'm wondering if there is a way to do this without using so many variables to do it? I am using underscore if this makes it easier. It would be cool if there was a much more elegant (and hopefully) simple way to achieve this. I mean, this method works fine for me, however I am trying to improve my javascript skills, and use less code when possible :). Thanks!