JavaScript for Line of Business Applications

Bosonic is a set of tools that enable you to build and use reusable Web Components now ! By leveraging the power of DOM to build high-level elements, you'll simplify your application code and benefit from 3rd-party elements.

What we wanted was a way to build components as this spec describes, shielding ourselves against potential spec changes, and supporting not-so-modern browsers like IE9. And so Bosonic was born !

This post analyzes two versions of the same app, both the original (JavaScript) version and the Dart version. The original version is a proxy for any small JavaScript app, there's nothing particularly special about the original version, which is why it made for a good example.

This post discusses the differences between the two implementations: file organization, dependencies and modules, shims, classes, type annotations, event handling, calling multiple methods, asynchronous programming, animation, and interop with JavaScript libraries. Finally, I detail the lessons learned.

One of our key products is a trading dashboard that handles hundreds of thousands of events from football matches and related betting markets. To consistently deliver value, we need to be able to handle this flurry of messages over a WebSocket connection and reliably keep the UI in sync.

At its peak, on a typical Saturday afternoon, each WebSocket connection will receive upwards of 500 messages per second. Translating each of these messages into a UI update yields incredibly bad performance: the incumbent dashboard does just that, but as the business has scaled, we are hitting the limits of the current solution.

So that we can continue to provide value to our users, we need to think about ways we can separate the concerns of receiving messages and updating the UI. Doing so has pushed us to evaluate our tech stack and rebuild portions of our dashboard from the ground up.

ngMessages is a new feature in AngularJS 1.3 for rending error messages in forms

Forms in AngularJS are a delight to work with since they naturally work off of the basics of how forms work in HTML. The ngModel directive peacefully works with form controls and the state of a form can easily be examined using the name of the form and the name of each input control. But what about displaying error messages? Since there is no set way of displaying error messages in forms, there are many inconsistent ways to do this in AngularJS. While showing and hiding a message is easy using ngIf or ngSwitch, making use of multiple messages across and entire application is where things get messy. Do we really have to use ngIf over 20 times for a form just to show a handful of messages? How can we reuse a template of messages in other parts of the application? Are forms really this complicated?

The new ngMessages module introduced in AngularJS 1.3-beta.8 is designed to render error messages in a reusable and maintainable way. Instead of having to butcher up your template code by placing ngIf statements everywhere, ngMessages listens on the `model.$error` object and then decides which messages to display based on what is present in the template.

Interested in learning more? let's explore the ngMessages and ngMessage directives in detail.

Essential.js is a simpler alternative to Underscore.js that gives you a solid base to get started with functional programming in JavaScript "the right way":

• All non-variadic functions with more than one argument are curried.
• Arguments are in proper order for better composition.
• Includes a few helpers not found in Underscore.
• Inspired by Brian Lonsdorf's talk, Hey Underscore, You're Doing it Wrong.

Declarative programming is when you write your code in such a way that it describeswhat you want to do, not how you want to do it. As such, it is left up to the compiler or interpreter to figure out the how. SQL and XSTL are both examples of declarative programming languages.

Imperative programming is telling the machine how to do something, with the end result being what you want to happen. As for examples, just about every programming language, including Visual Basic, Java, and C++, is imperative.

Typically, a language falls squarely into one of the two camps. JavaScript, the language of AngularJS, is a rare breed -- flexible enough to be used either way, so it's often used to present side-by-side comparisons. That being said, most of the examples that I've come across compare declarative programming to its functional equivalent. Functional programming is a form of declarative programming that implements a function-based approach to problem solving. Perhaps the most noteworthy ramification of the black-box approach of functional languages is that they are stateless; that is, the value returned by a function is wholly dependent on its input. Functions in imperative languages allow for the creation and transformation of data so that subsequent function calls may modify a variable.

This series of blog posts aims to provide a bit more theoretical overview of some of the AngularJS components in order to show you how the things you are already familiar with (like different Object-Oriented Design Patterns) fit in the picture.

The separation of concerns is achieved by dividing each AngularJS application into separate components, such as:

• partials
• controllers
• directives
• services
• filters