How to Build High-Performing Web Applications with AngularJS

Professional JavaScript developers are likely already familiar with Backbone.js and Ember.js, two open-source JavaScript frameworks and libraries providing RESTful JSON interfaces, respectively. However, if you aren't yet familiar with AngularJS(opens in new tab), you'll miss out on some compelling features that can significantly improve your HTML for web apps.  

Here, we'll offer you a taste of AngularJS, a superhero JavaScript MVW framework, an overview of how to get started using it, and some of its standout features.  

This should assist you in creating well-designed and stable rich online applications and provide compelling arguments for using AngularJS in your future work. Let's start!    

AngularJS: What is it?  

Google created AngularJS, an open-source web application framework that facilitates front-end development and testing for web developers. AngularJS primarily aims to extend online applications with MVC (Model-view-controller) functionality. It is a client-side JavaScript MVC/MVVM framework that operates without library dependencies, is extensible and performs admirably with other libraries. You can even change or replace any feature to suit your unique requirements.  

Adam Abrons and Miko Heverym, two Google engineers at the moment, created AngularJS in 2009. According to the official website, it is a "structural framework for dynamic web apps" most suitable for building one-page web applications that only need JavaScript, CSS, and HTML on the client side.  

It enables you to use HTML as your template language and enhance HTML syntax to represent the different parts of your web application clearly and concisely. AngularJS teaches the browser how to use dependency injection for any server technology, improving the structure of your JavaScript code and making it simple to test.    

Utilizing AngularJS  

With AngularJS, getting started is very simple. Adding a few attributes to your HTML scripts allows you to create a straightforward Angular application in about five minutes. Which are:  

1. Add the html> tag's "ng-app" directive. The page will become an Angular application by running AngularJS on it.   
2. After the head> tag, put the Angular script> element at the bottom of your page.  
3. Include typical HTML. HTML attributes are utilized to access AngularJS directives, and double-bracket notation is used to evaluate expressions.    
4. Include typical HTML. HTML attributes are utilized to access AngularJS directives, and double-bracket notation is used to evaluate expressions.  

The ng-controller directive defines a namespace where you may put your Angular JS to manage the data and evaluate HTML expressions. While the ng-repeat directive instructs Angular to create list elements as long as you have tasks to display, it is an Angular repeater object.  

While most frameworks today are simply collections of currently available tools, AngularJS is a next-generation framework with appealing features that benefit developers and designers. The amazing AngularJS capabilities listed below will aid developers in creating excellent web applications in the future.    

Directives  

One of AngularJS's most powerful and alluring features is the directives. They enable you to expand your HTML, and AngularJS uses them to integrate their action into the page. They let you supply unique, reusable HTML tags that can be used to change DOM attributes and control how certain elements behave. All directives are preceded with ng-, inserted in HTML attributes, and intended to be stand-alone components distinct from your MVC application.  

Several prominent AngularJS directives include:  

• ng-app: Angular is informed where to get activated by this directive. You only need to use one line of code to declare a page to be an Angular application: html ng-app>.  
• ng-bind instructs Angular to update the text of an HTML element as the value of the specified expression changes and to replace the element's text with the new value.  
• The ng-model directive connects the view to the model, which are other directives like select, textarea, and input requirements. It is quite similar to ng-bind.  
• Allows class attributes to be loaded dynamically with ng-class.  
• ng-controller: Using this directive to evaluate HTML expressions, you can define a JavaScript controller class.  
• Ng-repeat: It easily iterates across a collection item to which the specified loop variable is set.  
• Using the result of a Boolean expression, the ng-hide and ng-show directives determine whether or not an element will be shown.  
• If the criteria are true, the basic if statement directive ngIf enables the re-insertion of a copy of the compiled element into the DOM. The element gets removed from the DOM if the condition is false.  

The directive that listens for an event and adjusts its $scope as a result is shown in the example below.   

Binding of two-way data  

Data binding is arguably AngularJS's most important and distinctive feature. By lightening the load on the server backend, it prevents developers from having to write a significant amount of code. 80 percent of the code in a typical online application is devoted to navigating, traversing, and listening to the DOM. You may concentrate on other crucial components of your program because data-binding renders this code invisible.  

Most templating systems now use one-way data binding, which combines model and template elements into a view. Changes made to the model after the merger do not immediately appear in the display. The developer must manually modify the DOM components and attributes to reflect these changes. When a user modifies the view in any way, the procedure becomes more difficult and time-consuming. As a result, the developer must analyze the interactions, incorporate them into the model, and update the view.  

By managing data synchronization between the model and the DOM, and vice versa, AngularJS handles data-binding better and differently.   

Relying on Injection  

A built-in injector subsystem in AngularJS makes it simple for developers to create, comprehend, and test applications. In AngularJS, components are created, their dependencies are handled, and they are made available to other components upon request, thanks to dependency injection.  

AngularJS uses dependency injection to bring conventional server-side services to client-side web applications by reducing the backend load and making the web application much lighter.  

You must include a specific service as a parameter if you wish to use any of the core AngularJS services. When AngularJS detects that you wish to access that service, it immediately creates an instance for you.  

Additionally, you can create customized services and make them injectable.    

Templates  

A template for AngularJS is created using HTML and incorporates elements and properties unique to Angular. AngularJS renders the dynamic view in browsers by fusing data from the controller and model with the template.  

You can use the Angular components and attributes listed below:  

Filter: This component formats the data for display.  

Form controls: They are employed to verify user input.  

Markup: The double curly brace notation binds expressions to items.  

Directive: A directive is an element or attribute that renders a reusable DOM component or extends an existing DOM element.  

The CSS, HTML, and Angular directives for the template are often contained in a single HTML file called index.html in a typical application.   

Testing  

As JavaScript is dynamic and interpreted with significant expressive ability, it requires very little assistance from the compiler. The AngularJS team is, therefore, fully aware that any JavaScript code must pass a series of rigorous tests. Because of this, AngularJS was built from the ground up to be testable, making it as simple as possible for you to test your web apps.  

AngularJS fully utilize dependency injection, mocks are present, and behavior-view separation is encouraged. Protractor, an end-to-end test runner for AngularJS designed to remove test flakiness and replicate user interactions with your site, is available for end-to-end testing.