Knockout.js Troubleshooting Strategies. This post contains a number of tips, tricks, and strategies that I have used over the last couple of years to debug Knockout applications. Feel free to share some of your own tips in the comments or suggest other areas that you would like to see discussed. Binding issues The most common errors encountered in Knockout typically center around incorrect or invalid bindings.
Lazy? Hello, Knockout. This lesson is designed to be a high-level survey of Knockout.js’ main components. By implementing a concrete sample application, we’ll see how Knockout’s ViewModel, view, observables, and bindings interact to create a dynamic user interface. First, we’ll create a simple HTML page to hold all of our code, then we’ll define a ViewModel object, expose some properties, and even add an interactive binding so that we can react to user clicks. Before we start writing any code, download the latest copy of Knockout.js from the downloads page at GitHub.com. As of this writing, the most recent version is 2.1.0. After that, we’re ready to add the library to an HTML page.
Often times, I help users get their sample working in jsFiddle or make a fiddle that they can fork. I thought that it might be useful to have links to fiddles for all of the currently available samples. Introductory examples Detailed examples Contacts editor – original - in jsFiddleEditable grid – original - in jsFiddleShopping cart screen – original - in jsFiddleTwitter client – original - in jsFiddle Tutorials Introduction – original - in jsFiddleWorking with Templates and Lists - original - in jsFiddleSingle Page applications – original - in jsFiddle or full page hereCreating custom bindings – original - in jsFiddleLoading and saving data – original - in jsFiddle.
With the low-level DOM manipulation and events handling provided by jQuery this is fairly hard to achieve. You need a library providing you with more sophisticated way of communication between your UI and the underlying data model. And here is where Knockout comes in. Although you will need to use Knockout with jQuery at the same time, in some cases like animated transitions, Knockout itself doesn’t depend on it. Basic Concepts A model that holds your application’s data. 1. 2. 3. Trajectory Motion Simulator with HTML5/SVG/KnockoutJS. Introduction This article shows how one can write a simple trajectory motion simulator using SVG/KnockoutJS.
A trajectory motion is a very established body of physics that we have seen many applications in the real world. Among many real-world applications, trajectory motion has become the basis for many computer games these days. The very well known game that uses the trajectory motion is the famous Angry-bird game where a player can aim the angry birds with certain angle to create a trajectory motion to hit and crush the targets (castles, items, pigs).
There are 2 well established JS frameworks that we could combine to help us here: Knockout.js and D3. But can we make them work well together? The pieces – Knockout I assume you know roughly what Knockout.js and D3 are. Here’s a trivial view model that exposes an observable string: Which we can then bind to something in our view/HTML: Now whenever the view-model is updated, either in code (viewModel.foo("blah")) or by binding it to a control that accepts input, our UI will automatically reflect the change.
D3 is a library for creating data-driven documents. Phew. Of course, that’s just scratching the surface. Learn.knockoutjs.com.