Directives for AngularJS HTML DOM

Angular is an open-source web application framework based on Type-Script. AngularJS is also an open-source JavaScript-based web framework for dynamic web applications. It allows the usage of HTML as a template language. It also allows us to extend HTML syntax to express application components. AngularJS aims to increase browser applications with MVC (Model-View-controller) capacity. And also to reduce the amount of JavaScript that needs in web applications functions. Furthermore, Angular is faster in comparison with AngularJS. Angular has many good versions and the latest is version 1.7

Today AngularJS is one of the popular modern web frameworks. It helps to create rich internet applications. It consists of different templates and models. It makes the browser much smarter without using native extensions.

DOM (Document Object Model) in AngularJS acts like an API for JavaScript. Using DOM elements it can be defined as the logical structure of the documents and their manipulations. It also defines various methods and properties for all HTML elements. While loading a webpage, the browser creates a DOM for the respective page.  

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DOM is useful in AngularJS for the following reasons.

• Using DOM, a programmer can navigate document
•  structure.
• All documents are built by DOM elements.
• With the help of DOM, a programmer can add content and other elements.
• A programmer can alter the content using DOM.
• It helps to define the different properties of HTML

AngularJS architecture

AngularJS follows the MVC framework. It includes Model, Views, and Controller. Let us discuss it in detail.

The Controller part of this architecture represents the layer that contains business logic. Here, the user events trigger the stored functions inside the controller. User events are one of the parts of the controller. 

The views are presented to the end-user as a presentation. 

Models in this framework help to present the data. This data can be very simple or maybe complex as structured data. For example, if we are preparing a student application, then the data model consists of a student name and his ID. It could be different for other data models. 

There are different versions of Angular. But the most popular versions are Angular 2 & 4. These versions of Angular are helpful for the development of enterprise applications with better standards. Furthermore, Angular 4 is faster than version 2. Angular is much faster than AngularJS. There is a slight difference between Angular and AngularJS. Angular contains Typescript while AngularJS contains JavaScript. Moreover, it has a better algorithm for data binding and component-based architecture. These components are independent and make them reuse and test user-friendly.  

Directives in AngularJS

Most of the directives in AngularJS start with ng. Here ng means Angular. Directives in Angular are like markers on a DOM element. It informs AngularJS to transform the DOM element. It also extends the HTML element. 

The directives used to bind the application data to the attributes of HTML DOM are as follows. :-

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ng-disabled: It is used to disable the given control. Using this, the attributes of HTML elements can be disabled. The following syntax represents the directive.

<input type = "checkbox" ng-model = "enableDisableButton">Disable Button
<button ng-disabled = "enableDisableButton">Click Me!</button>

ng-show: This directive shows or hides the HTML element or the given control. The syntax for this directive is;

<input type = "checkbox" ng-model = "showHide1">Show Button
<button ng-show = "showHide1">Click Me!</button>

ng-hide: This directive of AngularJS hides the HTML element. The syntax is as follows; 

<input type = "checkbox" ng-model = "showHide2">Hide Button
<button ng-hide = "showHide2">Click Me!</button>

ng-click: It represents the click event in this directive. The syntax for the same is;

<p>Total click: {{ clickCounter }}</p>
<button ng-click = "clickCounter = clickCounter + 1">Click Me!</button>

The DOM or Document Object Model is useful for changing, manipulating and accessing the contents within the documents. It is possible only by using HTML or XML files. The directives of AngularJS represent the different activities of the DOM model.

There are some other types of AngularJS directives. Such as; Built-in Directives and Custom directives.

Built-in directives are predefined directives in a framework. We can directly use them in our applications. The built-in directives include ng-init, ng-model, ng-if, ng-repeat, ng-bind, etc. Whereas, Custom directives are created by self. We can define them by ourselves. 

Furthermore, the use of directives in AngularJS allows us the flexibility to create and customize elements in web applications. 

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What does AngularJS component requires ?

A component is AngularJS is a kind of directive which is simple to configure and also suitable for the applications based on components. This framework makes it easy to write or create an application.

The following are the benefits of using these components. :-

• These are easy and simpler to configure than plain directives.
• It promotes best practices.
• These are optimized for the component-based framework. 
• Writing these directives becomes easier.

Components never alter or change any data or DOM. In AngularJS, generally, it allows making changes to the data. The components contain a lifecycle. Components can only control their own data and views. But cannot change other DOM or data. 

Advantages of AngularJS

There are many advantages to AngularJS. The following can be discussed;

• It is an open-source framework. So, we can expect a small number of errors or issues.
• It provides two-way binding features. It helps to sync data and reduces the amount of writing JavaScript. It automatically syncs the HTML data.
• AngularJS supports both unit and integration testing.
• It also takes care of routing. It helps to move from one view to another. It is the key functionality of single-page applications. 
• It helps in extending HTML using directives. These features give more power to the web applications.
• Its Markups lives in DOM.
• Moreover, it uses plain JavaScript objects.
• It has a simple and improved architecture.
• It has a better declarative User Interface.
• Furthermore, it enables to reuse codes.
• It provides the convenience of testing.
• It has better server performance

Features of AngularJS

There are many great features of AngularJS. These include;

• The MVC framework is useful for dynamic modeling.
• It contains HTML UI, which helps it in various ways.
• It offers unit testing facilities.
• It provides different templates and models. 
• It uses different directives for different purposes. 
• Furthermore, it offers developers the option to write client-side applications.
• The applications are written using AngularJS to support different browsers.
• Moreover, this framework helps to build large scale, easy to use web applications
• Finally, its core features are, scope, data-binding, services, controller, filters, directives, templates, MVC, routing, etc.

Using AngularJS services, we can get data directly from the server. We can apply animations to our applications using this service. We can create and run different tests. Furthermore, we can move the application logic out of the application. Moreover, it helps to run end to end tests along with building simple applications.

Thus, the above writings explain the various Directives for AngularJS HTML DOM and its different features and advantages. The directives are useful for binding applications. There are many uses of these directives and their different types. It is a front-end JavaScript framework. Furthermore, It contains different features like MVC, Data Model binding, minimal code writings, unit testing, etc. To get deeper knowledge on AngularJS and its various directives along with its uses one can opt for Angularjs Online Training from various online sources. This learning will give a great skill along with a scope for enhancing my career successfully.