refactor underscore

refactor underscore.js

// Overall viewmodel for this screen, along with initial state
function ReservationsViewModel() {
    var self = this;

    // Non-editable catalog data - would come from the server
    self.availableMeals = [
        { mealName: "Standard (sandwich)", price: 0 },
        { mealName: "Premium (lobster)", price: 34.95 },
        { mealName: "Ultimate (whole zebra)", price: 290 }
    ];

    // Editable data
    self.seats = ko.observableArray([
        new SeatReservation("Steve", _.first(self.availableMeals)),
        new SeatReservation("Bert", _.first(self.availableMeals))
    ]);

    // Computed data
    self.totalSurcharge = ko.computed(function () {
        var sum  = _.reduce(self.seats(), function (sum, reservation) {
            return sum + reservation.meal().price;
        }, 0);
        return sum;
    });

    // Operations
    self.addSeat = function () {
        self.seats.push(new SeatReservation("", _.first(self.availableMeals)));
    };

    self.removeSeat = function (seat) {
        self.seats.remove(seat);
    };
}