JavaScript for Line of Business Applications

Animations aren’t just eye candy - they make your app feel faster. Unfortunately Ember still hasn’t settled on a standard method for animations.

Ember has been placing emphasis on the URL as the central “state” of a web application. There’s a great talk by Tom Dale talking about the importance of the URL. The amazing work done on the new router by Alex Matchneer means we now have a promise based system for transitioning between routes and loading models, which makes it a nice destination for adding animations.

My solution is to add a promise hook to both the entering and exiting of a route. Include this code after including ember.

The event emitter pattern was popularized by Node and is made available in the browser by libraries such as EventEmitter2. In practice, I haven’t seen a lot of use of event emitters in client-side applications, but lately I’ve been applying it more and more in my code. Here, I’ll introduce a modular approach to client-side development I didn’t invent, but which I decided to name anyway.

Anthony Bull overviews some of the tools that help being productive with Ember.js, providing details on Yeoman.

Writing scripts for your websites or web apps is often a simple process, you write your script, concatenate the file into your main scripts file and it gets pushed into the DOM. Not much to it, but when it comes to AngularJS, they believe in something slightly different...

No DOM manipulation should be carried out inside a Controller, the Controller is where most of your magic happens, a communications channel between your Model data and the browser. It can be tempting to simply whack in an existing script in there (as it'll work just fine), but this goes against Angular's principles.

So here's how to migrate one of your existing scripts or plugins across into a tightly coded AngularJS directive, this also makes code readability and reuse ultra-efficient, as Directives take the strain of repetative code out the window.

Directives are Angular's answer to Web Components 'Shadow DOM' but are compatible in all browsers (not just cutting edge HTML5 supporting ones) - bringing you the power of the future technology, today. Shadow DOM injects new content based on the element, has it's own CSS and JavaScript scope and introduces some incredible behaviour mechanisms, and this is what Directives mimic to bring you this technology today.

With the release of AngularJS 1.2 earlier this week, I have to say that the feature about which I am most excited is the "track by" augmentation for ngRepeat. This feature allows you to associate a JavaScript object with an ngRepeat DOM (Document Object Model) node using a unique identifier. With this association in place, AngularJS will not $destroy and re-create DOM nodes unnecessarily. This can have a huge performance and user experience benefit.

As I've blogged about before, when AngularJS renders an ngRepeat list, it injects an expando property - $$hashKey - into your JavaScript objects. It then uses this $$hashKey to associate your objects with the rendered DOM nodes. In the past, I've the hashKeyCopier library to manually manage these $$hashKey's such that I could updated the rendered collection with live data without causing unnecessary (and sometimes harmful) DOM changes.

I was hunting for jQuery performance tricks for a while to tune my heavy dynamic web app. After digging in a lot of articles decided to make a list of the best common performance tips. I also built a handy jQuery Performance Cheat Sheet that can be printed or placed on my desktop.

* Selectors performance tips
* DOM manipulation performance tips
* Events performance tips
* Testing jQuery
* General jQuery performance tips

I have been looking into various design patterns and trying to architect client side applications using it. More often than not the MVC pattern fits the requirement in most of the applications. However, I have found myself using MVVM (Model View - View Model) pattern along with MVC. I use MVVM pattern particularly when I have to maintain the state of the model on the client side. AngularJS provides great support by allowing you to extend the markup and tying the model right within the view (the markup). It also provides components that can be used to structure the application the MVC way and hence it's appropriately termed as MVW or MV* framework. However, I use BackboneJS in most of my applications and I have been able to maintain the state of the model using the Backbone.Stickit plugin.

I'm switching my node code from callbacks to promises. The reasons aren't merely aesthetical, they're rather practical:

Promises are throw-safe. If an error is thrown in one of the .then callbacks, only that single promise chain will die. I can also attach error or "finally" handlers to do any clean up if necessary - transparently! The process will happily continue to serve the rest of my users.

Promises are now part of ES6
Yes, they will become a part of the language. New DOM APIs will be using them too. jQuery already switched to promise...ish things. Angular utilizes promises everywhere (even in the templates). Ember uses promises. The list goes on.

But you said promises are slow!
Yes, I know I wrote that. But I was wrong. A month after I wrote the giant comparison of async patterns, Petka Antonov wrote Bluebird. Its a wicked fast promise library, and here are the charts to prove it...

Writing apps should be fun. This is a statement I try to keep in mind when approaching any application development. When I first realised that a full stack of Javascript can be used to create an application I was very happy, since for me coding in Javascript is a lot of fun. I was soon quite eager to neglect the traditional Java server-side + Javascript client, giving up the Java server side "bliss" and the constant context switching, in favor of a full stack of Javascript whenever I could.

On October 29th 2013 I gave a talk at the "Javascript.everywhere" meetup event, in which I presented the development route of Youtube Remote Control Application with a "slave" player using Javascript stack all over (NodeJS, Socket.IO, ExpressJS, AngularJS, MongoDB). I'm pleased to share the presentation and video.