The usage statistics posted on various websites indicate that AngularJS is currently one of the most widely used open source JavaScript frameworks. However, AngularJS is comparatively younger than other popular JavaScript frameworks. It is also maintained by a team of dedicated engineers at Google. Unlike other frameworks, AngularJS enables developers to create dynamic web application by using HTML as a template language. The web programmers can easily extend the syntax of HTML to express various components of the websites with clear and concise code. At the same time, AngularJS provides a number of features that help developers to build robust web applications within a shorter amount of time.
Features that Make AngularJS Different from Other JavaScript Frameworks
Extends HTML
HTML5, CSS3 and JavaScript make it easier for developers to create websites that look good on a variety of devices. While using HTML, the programmers have to use <div> tags frequently. Also, they need to use exhaustive CSS classes to express individual objects in the document object model (DOM) efficiently. These options affect the readability of code, and make it difficult for developers to maintain the websites. AngularJS is designed with a HTML compiler which allows developers to use HTML just like XML. The developers can further create several new HTML syntaxes simply by extending existing tags and their attributes.
Converts HTML into a Template Language
Unlike other JavaScript framework, AngularJS allows web developers to use HTML as a template language. The bracket system used in AngularJS’s template engine is pure HTML. Hence, the developers can simply make changes to the DOM for each template, and then pass the template as a DOM element to AngularJS’s template engine. They can further extend, execute and reuse the templates easily using the raw DOM components.
Expressions
As a MVC framework, AngularJS allows developers to keep the business logic and user interface separate. It further enables programmers to create views of the application by executing expressions directly within the HTML page. The programmers also have option to access JavaScript code in the expressions. Hence, they can use expressions to deliver content to users based on certain conditions and computations. However, they can use expressions only for performing small operations.
Directives
Unlike expressions, directives can be used for performing complex operations, and building large web applications. The programmers can use directives to structure web pages according to the available data. Also, they can use directives to extend HTML according to needs of individual web pages. The programmers also have option to use a variety of directives to accomplish common tasks. AngularJS allows developers to decide the elements to be displayed in each directive.
Data Binding
In addition to using directives of structure the views of a web application, the developers also have option to define the binding between content of the view and data in the scope. They can further use operations in the expressions and use specific directives to create bidirectional data binding. Each time the content of the view changes, the object in the scope is modified. Hence, AngularJS makes it easier for programmers to deliver updated and real-time information to users.
Filters
AngularJS further allows users to customize displaying of data on a web page through several mechanisms. The developers can use pre-built filters to display data in a web page in the most appropriate way. At the same time, they also have option to write custom filters to display data in the web page in a more compelling way.
Modules
AngularJS allows users to structure a web application through modules. They have option to create individual modules with controllers, filters, directives and service. Also, they can connect various modules and make them inter-dependent. Modules make it easier for users to convert the entire project into small and testable components which can be combined using dependency injection provided by the framework.
Dependency Injection
As noted earlier, AngularJS allows developers to divide the entire application into small modules, and combine the modules using dependency injection. While using dependency injection, the developers can use the config operation to retrieve specific elements of the application, and configure the element properly each time the module is loaded. AngularJS further allows developers to use dependency injection in a number of ways.
Routes
While using AngularJS, the developers can easily change the routes available in the web application using route providers. The option enables users to deliver the most relevant content and error messages to end users. They can create two distinct routes. One to deliver the appropriate content to authorized users, and the other to redirect to the error page. Also, the route providers make it easier for programmers to keep the web application structured and organized.
Controllers
The developers can store all behaviours of the web application in controllers while using AngularJS. The controllers can communicate with views through special operators called $scope. $scope enables the controllers to provide the appropriate functions and objects to the view. Also, the programmers have option to manipulate the functions and objects provided by controllers through expressions and directives, along with specifying the scope of data provided to the view.
Services
AngularJS allows programmers to create custom services, and inject these services into controllers seamlessly. The custom services can also be integrated with other services used by the web application. Likewise, the users can also define a public API which can be injected into the controllers, and used by other services. The feature makes it easier for developers to manipulate the functionality of third-party services used by the website.
REST Communication
The programmers can make the web application communicate with the restful server through two distinct services provided by AngularJS. They can use the connection using either $http or $resource. $http is designed as a small layer on top of XmlHttpRequest, whereas $resource supports higher level of abstraction. $resource further allows developers to make the application communicate with the restful server through custom actions. Hence, it becomes easier for programmer to effectuate the communication process by replacing POST and GET with custom actions.
It is also important for users to understand some of the major shortcomings of AngularJS. JavaScript lacks the advanced authentication and authorization options provided by modern server-side programming languages. As AngularJS is a JavaScript framework, it does not allow programmers to keep the web applications secure using authentication and authorization. Also, the framework requires end-users to enable JavaScript on their web browsers to access the website content fully. However, the developers can still take advantage of the features provided by AngularJS to reduce the amount of time and effort required for building dynamic web applications.
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