Forwarding arguments of variadic function calls.

gistfile1.js

function q(){
    console.log(arguments.length + " from q");
    var b = function(){
        console.log(arguments.length + " from b");
    }
    b.apply(this, arguments);
}

q();             //0 from q, 0 from b
q(1);            //1 from q, 1 from b
q(1, 2);         //2 from q, 2 from b
q(1, 2, 3, 1);   //4 from q, 4 from b
​

You are missing a semicolon in the variable declaration. Also, you should move that declaration to the top (i.e. var b;) to reduce confusion.

Also, your use of this will point to the global object in non-strict mode code and undefined in strict mode code if new is omitted. I would just pass null for thisArg.