Wednesday, October 22, 2014

A Different Angle: What is AngularJS?

This post covers my presentation, AngularJS from a Different Angle, that I presented to the Atlanta JavaScript Meetup group on October 20th, 2014. This was just over a week after the Atlanta Code Camp, when I presented Let’s Build an Angular App! Many of the attendees are local and might have attended both events so I wanted to make something unique.


It was then I realized that most Angular articles and presentations I see tend to walk through the Angular API. Did you know Angular has a factory? What about a service? It does dependency injection, and oh, let me tell you about the data-binding! Although that can be useful, what does it look like when you take a step back and view it from a higher angle? In other words, if I’m in charge of an upcoming project and am putting together my toolbox, how would I look at these frameworks?

Even before looking at features I’d probably want to know about real world use cases. How many times have you read a question posted that went something like, “Show me the money!” (Err, I know, it’s not really a question). In other words, what real world apps have been implemented with Angular? It’s one thing to point to a set of websites and say, “Look, that’s Angular.” It’s quite another to talk to someone on a team who built out an enterprise production app.

I’m a person that has done that several times and am happy to share the details. The largest app is one I share often because it really introduced me to the power and flexibility of Angular, and it went something like this:

  • 25 Developers at peak development
  • Globally distributed team with remote workers distributed across all international time zones (except perhaps a few bands that cross nothing but ocean)
  • 80,000+ lines of TypeScript code that probably generated to a lot more JavaScript code (but after minification/uglification I’m sad to report the codebase had only one single line of code)
  • Several hundred Angular components including directives, filters, controllers, services, etc.
  • 3 years of development (although Angular was introduced later into the cycle, which is important because it gave us insights into how it positively impacted the team)

About 6 months into the project we held a retrospective and decided to go with AngularJS and TypeScript based on a POC. After based on velocity and code quality we estimate between 2 – 4x speed of delivery of accepted code compared to before, and the team attributes a lot of that to Angular.

But What Is It?

If you want to look at it from a different angle, I believe Angular provides five fundamental services in an approach that considers testing a first-class citizen.


  • Declarative expressions
  • Glue
  • A container
  • Templates (not just talking UI templates)
  • Tools

To learn more, watch the video:


And follow along with the slide deck (links to code samples are on the last slide):


Sunday, October 12, 2014

Let's Build an AngularJS App!

This weekend I had the pleasure of attending the Atlanta Code Camp. It was a fantastic venue with sold out attendance and a variety of speakers covering cutting edge topics. I always try to submit a variety of topics but due to popularity, AngularJS won again! I've watched many talks that break down various facets of Angular and even some live coding demonstrations, but realized there haven't been many that cover building an actual, functional app with unit tests.

I structured the talk so that I could easily go from start to finish in stages. In the PowerPoint deck you'll see I have actual git checkout commands that reference the various commits. This will enable you to roll forward to each step after you've cloned the repository. The result is a responsive health calculator app that scales well to a variety of page sizes, has built-in validations for inputs and provides you with basal metabolic rate (BMR), body mass index (BMI), and target heart rate zones (THR). The app was developed using a test-driven (TDD) approach with a total of 83 specifications. The GitHub repository has full source and instructions.

Here is the deck. I hope you enjoy!

Jeremy Likness

Saturday, October 4, 2014

AngularJS Tip: Using a Filter with ngClass

I was working on my presentation of building an AngularJS app for the upcoming Atlanta Code Camp and ran into an interesting scenario. The app tracks various variables and formulas and then displays them in a responsive fashion. I’ll post the deck and code after the camp. One formula is Body Mass Index, an indication of general weight and health. I use it as an example but it is not the most accurate and a lean, muscular person may register as overweight or obese on the scale (read my non-technical article 10 Fat Mistakes to learn what you should really focus on).

For the session I want to show a test-driven approach, so I start out by defining what I expect from the formula using Jasmine:

describe("Formula for BMI", function () {
    describe("Given a 5 ft 10 person who weighs 300 pounds", function () {
        it("should compute a BMI of 43", function () {
            var actual = formulaBmi({
                height: 70,
                weight: 300
    describe("Given a 5 ft 8 in person who weighs 120 pounds", function () {
        it("should compute a BMI of 18.2", function () {
            var actual = formulaBmi({
                height: 68,
                weight: 120

Next I define the formula and ensure the test passes (notice at this stage I haven’t even involved Angular yet):

function formulaBmi(profile) {
    // BMI = (weight in pound * 703) /
    // (height in inches) ^ 2
    var bmi = (profile.weight * 703) /
        (profile.height * profile.height);
    // round it
    return Math.round(bmi * 10.0) / 10.0;

So that:

  • Formula for BMI
    • Given a 5 ft 10 person who weighs 300 pounds … should compute a BMI of 43
    • Given a 5 ft 8 in person who weighs 120 pounds … should compute a BMI of 18.2

Then I set the expectation it will register with Angular as a service:

describe("BMI Formula service", function () {
    var formulaBmiSvc;
    beforeEach(function () {
    beforeEach(inject(function (formulaBmiService) {
        formulaBmiSvc = formulaBmiService;
    it("should be defined", function () {
    it("should be a function", function () {
        var fnPrototype = {},
            isFn = formulaBmiSvc &&
            === '[object Function]';

… and I register the function with Angular to make the test pass:

(function (app) {
    app.factory('formulaBmiService', function () {
        return formulaBmi;

So that:

  • BMI Formula Service
    • should be defined
    • should be a function

To show the index I want to translate it to the scale it provides. Anything under than 18.5 is considered underweight, while anything over 25 is overweight and over 30 is considered obese.

Now I can write the tests for a filter that satisfies these conditions:

describe("BMI filter", function () {
    var bmiFilter;
    beforeEach(function () {
    beforeEach(inject(function ($filter) {
        bmiFilter = $filter('bmi');
    it("should be defined", function () {
    describe("Given BMI is less than 18.5", function () {
        it("should return Underweight", function () {
            var actual;
            actual = bmiFilter(18.4);
    describe("Given BMI is greater than or equal to 18.5 and less than 25", function () {
        it("should return Normal", function () {
            var actual;
            actual = bmiFilter(18.6);
    describe("Given BMI is greater than or equal to 25 and less than 30", function () {
        it("should return Overweight", function () {
            var actual;
            actual = bmiFilter(26);
    describe("Given BMI is greater than or equal to 30", function () {
        it("should return Obese", function () {
            var actual;
            actual = bmiFilter(31);

… and the filter itself:

(function (app) {
    app.filter('bmi', function () {
        return function (input) {
            var value = Number(input);
            if (value >= 30.0) {
                return 'Obese';
            if (value >= 25.0) {
                return 'Overweight';
           if (value < 18.5) {
                return 'Underweight';
            return 'Normal';

So that:

  • BMI filter
    • should be defined
    • Given BMI is less than 18.5 … should return Underweight
    • Given BMI is greater than or equal to 18.5 and less than 25 … should return Normal
    • Given BMI is greater than or equal to 25 and less than 30 … should return Overweight
    • Given BMI is greater than or equal to 30 … should return Obese

Now that I have the filter, I can use it to show the text for the current BMI:

b>{{ctrl.bmiValue | bmi}}</b>

This will show the title, the actual numeric BMI value and the designation of Underweight, Normal, Overweight, or Obese.

The problem I have is that I want to apply a class and show it in light red for the underweight and overweight conditions, and dark red for the obese condition. I could use ng-class and simply redefine the ranges like this:

<div ng-class="{ obese: ctrl.bmiValue >= 30 }"></div>

… but that feels like duplicating code. Fortunately, the ng-class directive supports having an expression passed in. What it evaluates to is what it will use as the class. So, I simply define it like this:

<div class="tile"
     ng-class="ctrl.bmiValue | bmi"
     title="Body Mass Index">...</div>

And ensure my CSS is set up correctly :

div.Obese {
    background: red;
} div.Overweight {
    background: lightcoral;
} div.Underweight {
    background: lightcoral;

Now I’m good to go. If you are concerned that the classes don’t follow convention (they are uppercase) and maybe need a more unique name (such as a prefix to avoid collisions) the solution is simple: add a parameter to the filter and based on that parameter, return the readable text or the translated class. Either way you encapsulate the logic in one place for reuse throughout your app.

Here’s a snap of the result scaled to a mobile form factor:


If you are in the Atlanta area and reading this before October 11, 2014, please come join us at the code camp. It is a day loaded with great sessions. Until then, enjoy your Angular coding!