Function to return nested values in an object

Function to return nested values in an object

This obviously needs to be improved upon, but the idea is there:

var obj = {
    "one" : {
        "two": {
            "three": 3
        }
    }
};

var arg = ["one", "two", "three"];

nestedValue = function(obj, arg) {
    var len = arg.length;

    if (len) {
        if (typeof arg == "string") {
            return obj[arg];
        }

        else {
            while (arg.length) {
                var key = arg.shift();

                if (!obj[key]) {
                    return undefined;
                }

                else if (typeof obj[key] === "object") {
                    return nestedValue(obj[key], get);
                }

                else {
                    return obj[key];
                }
            }
        }
    }

    // not found
    return undefined;
};

nestedValue(obj, arg);

If there's an easier way to do this, please clue me in : )