Knockout.js - Javavascript Data Binding and MVVM

Slide Deck for the knockout.js presentation given at CodeCampNYC September 15, 2012

Transcript

1. Boulos Dib September 15, 2012
2. MARQUEE SPONSOR
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8.  Independent Consultant – Napeague Inc.  First Commercial Personal Computer 1980 – TRS-80 Model III  First Z80 based product (Protocol Adaptor For Citibank– 1984)  First Commercial MS-DOS product (Telex/IBM PC, 50 Baud – 1985)  Started Windows Development using 16-bit Win 3.x  Used: 8080/Z80, 68xxx, PDP/RSX,VAX-VMS and x86 (C, C++, C#)  User Group/Meetup Co-Organizer:  New York Pluralsight Study Group, XAML NYC  Other interests:  Windsurfing, Guitar Playing
9.  Introduction to Knockout & MVVM  Built-in bindings  Custom bindings  Templates
10.  Simple development pattern.  MVVM, aka MVVC, sometimes MVC or MVP  Separation of concerns (Pattern)  Separates Model and UI  Separates Behavior and Structure  Popular with WPF & Silverlight developers.  Data Binding makes it easy to implement MVVM.
11. Web Application  The 100K foot level view, Web Application  Models, Controllers and Views Views Models Controllers DB Partial Views Routes Services Partial Views Partial Views Code & Markup Routes Routes Code Services Services Code
12. Browser  The browser level view  HTML/CSS – JavaScript - JSON View HTML & CSS Model JSON ViewModel JavaScript {a: b } var x; <h1>
13.  Javascript Library to simplify dynamic UIs with automatic refresh.  Core Concepts  Declarative Bindings  Dependency Tracking  Templates  Extensible
14.  If using ASP.NET MVC  NuGet Package Manager  Download  knockoutjs  jQuery
15.  Observable  Computed Observable  Observable Arrays  Declarative bindings  Template Support
16.  Create the Model  Retrieve Data: usually via Ajax or other form data retrieval (API, LocalStorage).  Create the ViewModel  Encapsulate UI behavior and data from model.  Create the View (HTML Markup)  <label data-bind=“text: name” />  Bind the ViewModel to the view  applyBindings(viewModel)
17. First Name: <input type="text“ data-bind="value: firstName"/> Last Name: <input type="text" data-bind=“value: lastName" /> <span data-bind="text : firstName"></span> <input type="text" data-bind="value : lastName" /> var viewModel = { firstName: ko.observable("John"), lastName: ko.observable("Doe") }; ko.applyBindings(viewModel);
18. var vm = { quantity: ko.observable(10), price: ko.observable(100), taxRate: ko.observable(8.75) }; viewModel = new vm(); viewModel.totalCost = ko.computed(function () { return (parseInt("0" + this.quantity(), 10) * this.price()) * this.taxRate(); }, viewModel); ko.applyBindings(viewModel);
19. var viewModel = { States: ko.observableArray([ { State: "New York", Cities: ['New York City', 'East Hampton', 'Yonkers'] }, { State: "New Jersey", Cities: ['Jersey City', 'Hoboken', 'Maplewood'] }, { State: "Connecticut", Cities: ['Stamford', 'Greenwich'] }, { State: "Pennsylvania", Cities: ['Philadelphia'] }, ]), selectedState: ko.observable(), selectedCity: ko.observable() }; viewModel.selectionMade = ko.computed(function () { return (this.selectedState() && this.selectedCity()); }, viewModel); ko.applyBindings(viewModel);
20. Type Description visible Used to hide or show DOM elements text Display text value in a DOM element html Display html in a DOM element css Add or remove CSS classes from DOM elements style Apply specific style to a DOM Element attr Set the value of any attribute on a DOM element
21. binding Description foreach Used for rendering lists based on array bindings. If Conditional inclusion of markup and any related binding based on truthy condition Ifnot Conditional inclusion of markup and any related binding based on a falsey condition with Creates a new binding context changing what descendent element bind to.
22. binding Description click Add an event handler so a function is invoked when the associated DOM element is clicked. event Add an event handler than can be bound to any event, such as keypress, mouseover or mouseout. submit Event handler used when submitting forms. enable Used to enable DOM elements only when the parameter value is true. Typically used with form elements like input, select, and textarea. disable Opposite of enable. Used in the same way.
23. binding Description value Associates a DOM’s element value with a propery on the viewmodel. hasfocus Two way binding for setting focus on an element and chekcing whether an element has focus. checked This binding is used for checkable controls. Radio button or checkbox. options Used to bind the elements of a drop-down list or multi-select list. selectedOptions Bind to elements that are currently selected. Used with select and options bindings. uniqueName Gives an element a unique name if it does not already have a name attribute.
24. // Subscribe myViewModel.totalCost.subscribe(function(newValue) { alert(“Let’s check if we are above our budget" + newValue); }); // Dispose of subscription var subscriptionCost = myViewModel.totalCost.subscribe(function(newValue) { /* do some work */ }); // ...then later... subscriptionCost.dispose();
25.  Custom Bindings  Plugins  TodoMVC  http://addyosmani.github.com/todomvc/  Knockbackjs  http://kmalakoff.github.com/knockback/  KnockoutMVC  http://knockoutmvc.com/
26.  Named Templates  Anonymous Templates  Inline  External
27.  Register a binding by adding it as a subproperty of ko.bindingHandlers.  Need to supply two functions:  init  update  And then use it with DOM element bindings. <div data-bind=“customBindingName: someValue"> </div>
28. ko.bindingHandlers.customBindingName = { init: function (element, valueAccessor, allBindingsAccessor, viewModel) { // This will be called when the binding is first applied to an element // Set up any initial state, event handlers, etc. here }, update: function (element, valueAccessor, allBindingsAccessor, VM) { // This will be called once when the binding is first // applied to an element, and again whenever the associated // observable changes value. // Update the DOM element based on the supplied values here. } };
29.  Main Site (Steve Sanderson - Author)  http://knockoutjs.com  Ryan Niemeyer - Contributor  http://www.knockmeout.com
30.  Contact:  http://blog.boulosdib.com  @boulosdib