A Better Way to Learn AngularJS

Introduction

Note: Looking to learn the latest version of Angular? Take the "A Better Way to Learn Angular 2" tutorial

Congratulations on taking the plunge!

This AngularJS course is built with the intent of exposing you to the best available resources on each Angular topic. Our desire is to present these topics richly, and from a variety of vantage points, in order to afford you a more complete perspective on them.

The learning curve of AngularJS can be described as a hockey stick. Getting started with apps featuring basic functionality is delightfully easy. However, building more complex apps often require understanding Angular's inner workings. Failure to do so will cause development to become awkward and cumbersome.

With AngularJS, the "Ready, Fire, Aim" learning methodology of duct taping together a handful of tutorials and a cursory glance through the documentation will lead to confusion and frustration. This curriculum is designed to properly guide you through each of the key Angular concepts thoroughly with a broad exposure to high quality content. With your eventual mastery of AngularJS, you will be able to fluently and efficiently construct large-scale applications.

Prerequisites

Resources

Since AngularJS is still in its infancy relative to other JavaScript frameworks, the number of encyclopaedic resources on it is still insufficient. Therefore, the curriculum will employ a healthy number of excellent blogs in order to offer a more meaty perspective on respective topics.

Kicking the Tires

AngularJS is not a library.

Rather, it is a JavaScript framework that embraces extending HTML into a more expressive and readable format. It allows you to decorate your HTML with special markup that synchronizes with your JavaScript leaving you to write your application logic instead of manually updating views. Whether you're looking to augment existing JavaScript applications or harness the full power of the framework to create rich and interactive SPA's, Angular can help you write cleaner and more efficient code.

When descending upon an entirely new topic, it is important to frame the topic correctly before diving into the minutia.

Read the following two entries in the AngularJS guide docs, they will give you a good idea of what you're about to get into. Don't worry about picking up on every aspect of the topics they glaze over, all of these will be covered thoroughly in subsequent lessons.

These resources go over a handful of topics that might be helpful in building the appropriate mental models while consuming the Angular curriculum. Some, probably most, of the terms will bounce right off you until you have gone through that section of the course, but it should provide valuable context when approaching a new topic.

Taking It for a Spin

One of the awesome things about AngularJS is its usability right out of the box. Very little information about how the framework operates is needed to get up and running with your first application.

Read the following AngularJS guides followed by lessons that we made to better expose each concept:

Binding

Controllers

Services

Additional Resources

The following set of guides will serve to reinforce many of the topics just covered, and explain some new ones in detail:

Promises

Promises are an immensely important part of the AngularJS framework and with the new ES6 spec, they're set to play an important rule in JavaScript as a whole.

Until native promises find their way into the browser, Angular uses a stripped down version of the Q promise library called $q.

AngularJS Documentation

Filters

Filters are a simple but powerful tool in Angular, used primarily to format expressions in bindings in views and templates.

Creating a filter

As shown in the video above, creating a filter to manipulate the output of an Angular expression is quite simple. Just by adding the filter name (in this case we're creating a filter called capitalize) after the pipe | lets Angular know it needs to execute the respective filter on this expression.

<input type="text" ng-model="test.myString" />
<h2>
  {{ test.myString | capitalize }}
</h2>

In order for this to work, we need to create a filter called 'capitalize' that will take the string returned from the Angular expression and capitalize all of the letters in it. Adding filters to your Angular application is done by invoking the filter method on angular.module like so: angular.module('app', []).filter('filterName', filterFunction);

Your filter function needs to return a function that will be executed every time Angular needs to evaluate that expression (if the model changes, etc). That function then needs to return the final string output:

function TestCtrl() {
  // basic controller where we preset the scope myString variable
  var self = this;
  self.myString = "hello world";
}

// this is where the filter magic happens.
function CapitalizeFilter() {
  // this is the function that Angular will execute when the expression is evaluated
  return function (text) {
    // text is the original string output of the Angular expression
    return text.toUpperCase();
    // and we simply return the text in upper case!
  }
}

angular.module('app', [])
.controller('TestCtrl', TestCtrl)
// define a filter called 'capitalize' that will invoke the CapitalizeFilter function
.filter('capitalize', CapitalizeFilter);

That's the general idea of how filters work in AngularJS. However, Angular also ships with some standard filters that you can use out of the box:

Additional Resources

Finally, the Angular guides offer a bit more depth on filters:

Directives

Now you're really getting into the meat of what makes Angular special. Directives are certainly one of the most important facets of the framework, and as such, this is one of the biggest sections of the course.

The general idea behind directives is this: what if you could create your own element and attribute types with corresponding functionality? With directives, you can create custom, reusable components for your application that make developing interactive UI widgets drastically easier. No more custom jQuery code every time you want put a UI widget on the screen; you just place your custom directives there instead!

Creating our first directive

Let’s see what it takes to create our very first directive. We'll start off by building a simple element called <welcome> that will display a custom message.

To begin building our directive, we will first create an angular module called "greetings" with no dependencies. Then we’ll just call the .directive method on angular.module and create a 'welcome' directive. The first parameter will be the name of the directive and the second will be a function for a callback. From this callback, we’ll return an object with a property called “restrict” which will restrict this directive to Elements. The object will also have the property “template” for specifying the HTML for our directive. For our template, we’ll make a div and we’ll say “Howdy there! You look splendid.”

angular.module('greetings', [])
.directive("welcome", function() {
  return {
    restrict: "E",
    template: "<div>Howdy there! You look splendid.</div>"
  }
});

Now that we have a greetings module with a welcome directive which is restricted to “E”, we can jump into our index, create our greetings app, and create our element here, which is the welcome directive.

<body ng-app="greetings">
    <welcome></welcome>
</body>

Once we load the page and check it out, you can see it says, “Howdy there! You look splendid” - and that’s all there really is to writing your very first directive.

We’ll get into the details of what’s going on here in the next few lessons. Basically, as soon as you have an app you can attach directives to that app or module, and in your HTML make sure you define your elements inside of your app.

Building a 'tab' Directive

To see a good example of some of these concepts in action, head through our course on building a tab widget:

Advanced Directive Topics

Many of the concepts below are covered in the Tab Directive course but the modules below may help clear up any lingering confusion.

Interestingly, scopes within directives are dramatically underrepresented in mainstream Angular resources compared to how important they are. A solid understanding of scope mechanics is essential when scaling applications, as well as writing modular and testable code. These resources provide good insight on the topic:

Additional Resources

To wrap up, the Angular guides offer a bit more detail on the specifics of some aspects of directives:

The View and the DOM

This section is a bit of a hybrid of seemingly unrelated topics, DOM manipulation, $watch, and view services, but they are closely related, as they all live in close proximity around the application's views in implementation.

The egghead videos do a superb job of tying these topics together:

Additional Resources

Animations

Animations are a really important part of user interfaces. Fortunately, Angular provides some good tools for making this easy.

Additional Resources

Templates

Despite this being a short section, understanding Angular templates is critical to being able to build applications effectively.

This tutorial is an excellent primer on the subject:

Additional Resources

The documentation guide also has a quick but quality piece on Angular templates:

Routing

Angular routing, while not unduly complicated, does introduce a large number of concepts all at once. It also will handle the lion's share (or close to it) of logic for many single page applications. It should then be no surprise that this is the largest section of the course.

The following lessons appropriately devote a great deal of podium time to routing:

Additional Resources

Finally, the Angular docs have a great section on the $location service:

$http and Server Interaction

A core requirement of web applications is the need to communicate with other servers. AngularJS allows you to easily do this using the $http service.

In addition to $http, Angular offers a higher level service called $resource, which abstracts away RESTful communication by creating objects that represent routes. The abstraction can often get in the way so $http tends to be the better bet, however $resource can be pretty convenient when communicating with very well defined APIs. If you're interested, the following tutorial gives a pretty good overview:

Additional Resources

Under the Hood

At this juncture, it's appropriate to dive into the niceties of AngularJS. In order to truly master the framework, hand-wavy arguments for how things work aren't sufficient anymore. You need to get into the nitty-gritty of what makes Angular tick.

These egghead videos offer an excellent primer for some increasingly advanced topics:

Additional Resources

Finally, there are a healthy number of Angular documentation guide pages that really get down into dissecting Angular. These are some of the best resources on Angular's innards out there, make sure and fully take them in:

Development Environment and Testing

Much of Angular's design is built around being highly testable. Central to this is the widespread utilization of dependency injection, which you read about in Chapter 11. Not only this, but with tools like Yeoman available, a robust test suite becomes realistic and manageable.

There is only one egghead video on testing, and it gives a simplistic overview of a unit test on a filter. (It's worth mentioning that the Testacular test runner is now called 'Karma'):

Meet the Gang

A person new to testing might be a little overwhelmed with these concepts and how they play together in the world of testing. This reference should help out:

  • Yeoman has the scaffolding tool yo that generates an application skeleton to start out with, complete with things like Bootstrap or a pre-configured testing setup. The scaffold of the application is different in many ways to the angular-seed scaffold, but it is important to note that they both use Karma and Jasmine in the same ways.
  • angular-seed is a ready-to-eat AngularJS scaffold available on their github with directory structure and testing amenities pre-prepared. Testing this application is accomplished by running a standalone Karma test server.
  • Grunt is the testing tool used in Yeoman, but it is used as a wrapper for Karma.
  • Karma is the actual test runner that is used to test AngularJS. It can be used standalone from Grunt. Karma circumvents testing inconsistencies across browsers, which would happen with things like PhantomJS, by actually launching a browser and running the tests in it.
  • Jasmine is the testing framework which is used for unit tests by default in Karma. Angular E2E tests with Karma don't and can't use the Jasmine adapter, although E2E tests use very similar syntax with the Angular Scenario Runner. This blog post does a fine job of going through how to actually author some Jasmine tests, and gives some excellent examples.

Additional Resources

Now that we have fleshed out how testing should generally go, let's take a look at the Angular docs on testing. These are going to give some more information on how to think about Angular testing. While they are a good resource to have, regrettably, some of them are not yet complete.

More Readings and Examples

Deploying to Production

At Some point you're going to want to deploy your application to production and code minification is an important part of that process. Unfortunately, the nature of Angular's DI system can create issues. These issues can be resolved using explicit dependency injection:

Adding and maintaining dependency annotations can be a tedious process. Fortunately there exists and excellent tool for automating this process:

Examples and Analysis

At this point, most of the core Angular topics have been covered, and it's appropriate to get into some examples. We've written a handful of in depth courses that will teach your how to build fully fledged Angular apps:

Additional Resources

Last, we recommend working through the AngularJS documentation tutorial. The format they present it in is a bit too hands-off to be exceedingly helpful, so we recommend playing around with it and modifying it to get the most out of the exercise.