AngularJS 1.x, Part 1: Introducing Angular

AngularJS is a popular framework that takes care of many common tasks, such as data binding, routing, and making Ajax calls, allowing developers to focus on the unique aspects of their application. Angular makes it much easier to maintain a large, complex single page application.

Angular is an open source project that you can use for free and contribute to (if you are skilled and ambitious).

As of this writing, AngularJS is on version 1.x. The Angular team is still actively working on the 1.x version; but they have already begun work on AngularJS 2.x, which is a complete rewrite of the Angular framework. AngularJS 2 is currently in beta and features some different paradigms than AngularJS 1. This series will initially focus on AngularJS 1, which has been out of beta for many months. In the future, after AngularJS is out of beta, I hope to write more about that version.

To get started with Angular 1, you need to add a reference to the Angular libraries.

You can either download the Angular files from http://angularjs.org or you can point your browser directly to the files on the Angular site. In either case, you need to add a reference to the Angular library, as in the examples shown below.

<script

src="https://code.angularjs.org/1.5.0-rc.0/angular.js">script>

<script src="angular.js">script>

Angular uses directives to declaratively add functionality to a web page. A directive is an attribute defined by or within Angular that you add to the elements within your HTML page.

Each Angular page requires the ng-app directive, as in the examples below.

<html ng-app>

<html ng-app="MyApp">

The second example specifies a Controller, which is a JavaScript function that contains some code available to the entire page. We'll talk more about Controllers in a later article.

You can add this attribute to any element on your page, but Angular will only work for elements contained within the attributed element, so it generally makes sense to apply it near the top of the DOM (e.g., at the HTML or BODY tag). If I add ng-app to the HTML element, I will have Angular available throughout my page; however, if I add ng-app to a DIV element, Angular is only available to that DIV and to any elements contained within that DIV. Only one ng-app attribute is allowed per page and Angular will use the first one it finds, ignoring all others.

Once you have the SCRIPT reference and the ng-app attribute, you can begin using Angular. A simple use of Angular is one-way data binding. There are several ways to perform data binding in Angular. The simplest is with the {{}} markup. In an AngularJS application, anything within these double curly braces is interpreted as data binding. So, something like

The time is {{datetime.now()}}

will output the current date and time. Below are a few other examples.

<h3>{{"Hello" + " world"}}h3>

<div>{{5+2+3}}div>

which will output the following:

Hello World
10

If your controller contains variables, you can use those as well, such as:

<div>{x} + {y} = {x+y}! div>

Although working with AngularJS can be complex, it only takes a small amount of code to get started.

You can see a live example of the concepts above at this link.

In this article, we introduced the Angular JavaScript framework; then, showed how to add it to your web application and perform simple, one-way data binding.