learn.knockoutjs.com - Working with templates and lists

http://learn.knockoutjs.com/#/?tutorial=templates

by JasonMore

HTML

<link rel="stylesheet" href="http://learn.knockoutjs.com/Content/App/coderunner.css">
<link rel="stylesheet" href="http://learn.knockoutjs.com/Content/TutorialSpecific/templates.css">
<script src="http://github.com/downloads/SteveSanderson/knockout/knockout-2.1.0.js"></script>
<body class="codeRunner"> 
    
    <h2>Your seat reservations (<span data-bind="text: seats().length"></span>)</h2>
    
    <table>
        <thead><tr>
            <th>Passenger name</th><th>Meal</th><th>Surcharge</th><th></th>
        </tr></thead>
        <tbody data-bind="foreach: seats">
            <tr>
                <td><input data-bind="value: name" /></td>
                <td><select data-bind="options: $root.availableMeals, value: meal, optionsText: 'mealName'"></select></td>
                <td data-bind="text: formattedPrice"></td>
                <td><a href="#" data-bind="click: $root.removeSeat">Remove</a></td>
            </tr>    
        </tbody>
    </table>
    
    <button data-bind="click: addSeat, enable: seats().length < 5">Reserve another seat</button>
    
    <h3 data-bind="visible: totalSurcharge() > 0">
        Total surcharge: $<span data-bind="text: totalSurcharge().toFixed(2)"></span>
    </h3>
    
</body>

JavaScript

// Class to represent a row in the seat reservations grid
function SeatReservation(name, initialMeal) {
    var self = this;
    self.name = name;
    self.meal = ko.observable(initialMeal);

    self.formattedPrice = ko.computed(function() {
        var price = self.meal().price;
        return price ? "$" + price.toFixed(2) : "None";        
    });    
}

// 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", self.availableMeals[0]),
        new SeatReservation("Bert", self.availableMeals[0])
    ]);

    // Computed data
    self.totalSurcharge = ko.computed(function() {
       var total = 0;
       for (var i = 0; i < self.seats().length; i++)
           total += self.seats()[i].meal().price;
       return total;
    });    

    // Operations
    self.addSeat = function() {
        self.seats.push(new SeatReservation("", self.availableMeals[0]));
    }
    self.removeSeat = function(seat) { self.seats.remove(seat) }
}

ko.applyBindings(new ReservationsViewModel());