Learn to Build Modern Web Apps with AngularJS and Ruby on Rails

Jumping in with Angular

Get started with AngularJS by exploring the syntax with built-in directives and filters

To begin this tutorial, we're going to start with the Angular side of things. AngularJS is a frontend framework developed by Google with the goal of making single page web applications easier to build, test, and maintain. Throughout this tutorials, we'll be linking to our A Better Way to Learn Angular guide which can provide supplementary information.

Without further ado, let's jump in...

Getting Started

As mentioned before, this tutorial will take you through building out a Hacker News/Reddit clone, which we're going to name "Flapper News". To keep things simple, we're going to kick things off with two files.

Create two empty files called index.html (for writing the template) and app.js (for defining our AngularJS logic)

To begin, our index.html will look like this:

    <title>My Angular App!</title>
    <script src=""></script>
    <script src="app.js"></script>
  <body ng-app="flapperNews" ng-controller="MainCtrl">

Our app.js is going to look like this:

angular.module('flapperNews', [])
.controller('MainCtrl', [
  $scope.test = 'Hello world!';

With these several lines of code, we've set up a new AngularJS app and created a new controller. You'll notice that we declare a variable test in the controller and display its contents using the AngularJS {{}} notation. This is demonstrating one of the most powerful features of AngularJS, which is its two-way data-bindings.

If you aren't familiar with data-binding in AngularJS, read the AngularJS Guide on two-way data-binding

Displaying Lists

One thing that's is going to be absolutely fundamental to our app is displaying lists. Fortunately, angular makes this really easy using the ng-repeat directive.

To begin, we're going to modify our controller to include a new $scope variable that defines a list of post titles on line 8 in app.js:
$scope.posts = [
  'post 1',
  'post 2',
  'post 3',
  'post 4',
  'post 5'

The $scope variable serves as the bridge between Angular controllers and Angular templates. If you want something to be accessible in the template such as a function or variable, bind it to $scope

Now that we have a list of data we want to repeat, let's use ng-repeat to do it. Add the following code to line 8 of index.html, replacing the div that was there before:
<div ng-repeat="post in posts">

When you refresh the page you should see a list of posts!

Now what if we want to display additional information about our posts? ng-repeat lets us do that too!

Let's amend our posts object to include some additional information we might be interested in displaying like the number of upvotes:
$scope.posts = [
  {title: 'post 1', upvotes: 5},
  {title: 'post 2', upvotes: 2},
  {title: 'post 3', upvotes: 15},
  {title: 'post 4', upvotes: 9},
  {title: 'post 5', upvotes: 4}
Now we change our ng-repeat directive to display the new information:
<div ng-repeat="post in posts">
  {{post.title}} - upvotes: {{post.upvotes}}

Of course it is important to order posts by number of upvotes, and we can tap into an angular filter to make it happen.

Add a filter to our posts based on the number of upvotes in descending order:
<div ng-repeat="post in posts | orderBy: '-upvotes'">
  {{post.title}} - upvotes: {{post.upvotes}}

AngularJS comes with several built in filters but you can also write custom filters tailored to your specific needs.