AngularJS: How to Begin

AngularJS is the Javascript framework for website development. It is widely popular for the features including modularity and separation of concerns. Here are some of the keywords you must be familiar with in order to build web applications with AngularJS.

Steps to Create

Here are the steps to create an application with AngularJS:

  1. Download the latest angular js file from the Angular website. Or, you can include the CDN in the script tag of your web page
  2. Bootstrap the application with Angular by using ng-app
  3. Create a controller in the app
  4. Create the HTML view in the body
  5. Run the application in a web browser




Angular Keywords

  1. Directives: AngularJS uses the directives to convert static HTML into dynamic Document Object Model (DOM) with the help of special attributes such as:
    1. ng-app: To determine which part of the page will use Angular. It will load the respective module in that part.
    2. ng-controller: To identify which Javascript controller should be used in that part of the page.
    3. ng-model: To determine the binding between model and the input field ensuring two way binding.
  2. Modules: Modules ensure separation of concerns in manageable units. It can comprise all the directives, expressions, controllers, services, and filters. Modules specify how an application can be bootstrapped. Advantages of using modules are:
    1. Easy to declare and understand
    2. Code can be packaged as reusable chunks
    3. Easy to load in any order or load in parallel
    4. Faster unit tests because only relevant modules can be tested
    5. Modules can be used in end-to-end tests to override configuration
  3. Controllers: Controllers are defined by a JavaScript constructor function that is used to augment the Scope. They carry the business logic and determine how the view and model interact. The scope is a mandatory parameter that is passed to the controller.
    1. A controller is attached to the DOM via the ng-controller directive.
    2. Then,  Angular instantiates a new Controller object, using the specified Controller‘s constructor function.
    3. A new child scope will be created and made available as an injectable parameter to the Controller’s constructor function as $scope.
  4. Expressions: Expressions are Javascript code snippets that are placed in dual curly braces. {{ }}. They are used to load model directly into the view. Advantages of using expressions are:
    1. Evaluated in the current scope not in the global window
    2. Evaluation of errors is either null or undefined
    3. Loops, functions, exceptions cannot be handled in Angular expressions
    4. You need to create a controller for complex Javascript functions



  5. Scope: Scope is an object of the application model. It refers to the current context or boundary of the application. Scope establishes a connection between application controller and view. Some of the characteristics of the scope are:
    1. Used to observe model mutations
    2. Used to propagate events similar to DOM events
    3. Can be nested to limit the properties and behavior of application components
    4. A child scope can inherit from the parent scope
    5. Provide a context for expressions to evaluate

There are some other key terms such as filters, forms, routing, and services which are key to an Angular application.

Forget Everything: Just Learn AngularJS!

Angular or AngularJS is the next most powerful Javascript framework out there which is becoming increasingly popular among the tech world. Angular JS along with CSS frameworks such as Bootstrap coupled with the REST services is redefining Website development.

AngularJS

AngularJS was developed by Google and is the most important Javascript framework which makes easier for the developer to maintain the code and achieve the same and better functionality achieved with Javascript. The best part of AngularJS is that it is open source and is having the largest support available of all the frameworks available. The current stable version is 1.4.7 and Angular 2.0 is on the way!

Advantages of AngularJS

AngularJS is similar to Javascript and it can enhance the HTML which will enable it to achieve client side programming. It has inbuilt JQuery support called JQLite which helps us in utilizing almost eighty percent of functions in JQuery library.

Browsers

AngularJS has inbuilt multi-browser support and it works on any browser such as Chrome, Opera, Firefox, Safari, and Internet Explorer. You can access your website from any device, tablet, computer, or desktop. Large-scale Enterprise applications can be developed using AngularJS. AngularJS is widely used for developing Single Page Applications (SPA) which are super light and super fast at the same time delivering unbelievable amount of data to the user.

Design

AngularJS facilitates rapidly changing user requirements and business needs at the same time leveraging the skill sets of Front end web developers. Separation of concerns that is defining the model, view, and controller-makes it easier for modular programming and keeping any changes manageable. Dependency injection and use of patterns is simple with AngularJS. Angular supports the very popular Model View Controller pattern(MVC), Model View View Model (MVVM) pattern, and Model View Whatever (MVW) pattern. AngularJS also supports responsive design which is way more important for modern day websites.

Testing

AngularJS is also super good for testing as it allows testing of Model and Controllers in isolation. AngularJS is designed to run unit testing with Karma, Jasmine and Angular mocks. The interactions between View and other components requires mocking framework to unit test. This can be achieved with AngularJS.

Prerequisites

To learn AngularJS, you must be familiar with Javascript, HTML, CSS, and website development. You also need basics of Java, PHP, and MySQL. You can download the latest version from the Angular website or include the CDN in the script tag of your web page.