For creating client applications in HTML and TypeScript, the Angular 7 was designed as a platform and framework which is written in TypeScript. The core and optional functionalities are thus implemented by Angular 7 as a set of TypeScript libraries to be imported into an app. For an Angular 7 application, NgModules are considered to be the basic building blocks because the compilation context for components is provided by them. A set of NgModules defines an Angular 7 app. The related code is collected into functional sets by the NgModules.
Along with having a minimum of a root module always to enable bootstrapping, an Angular 7 app can also have many other feature modules.
- The sets of screen elements that are chosen and modified as per the logic of a program and data by Angular 7 are called views in Angular 7 and are defined by the components.
- Services in Angular 7 serves specific purposes not directly related to views and are used by the components. To make a code modular, reusable, and effective the Service providers can be introduced into the components as dependencies.
Just like services, Components are simple classes with decorators. They mark their types and present metadata to guide Angular to serve. The root component is always included in every Angular application as a component. A page hierarchy is connected with page DOM by using the root component. A class is defined by each component to include application data and logic. Each component is associated with an HTML template. It specifies a view to be displayed in a target environment.
Metadata of Component class:
- A component class is associated with a template that defines a view by the metadata for that component class. The ordinary HTML is combined with Angular directives and binding markup by a template. Thus, the Angular is allowed to modify the HTML before executing it for display.
- The information that the Angular needs to provide to the components through dependency injection (DI) is facilitated by the metadata for a service class.
- Own functionalities are allowed by the NgModules that can be exported and used by other NgModules. For instance, import the Router NgModule to use the router service in an app.
Template, Directives and Data Binding:
To combine HTML with Angular Markup, the template is used in Angular 7. It also modifies the HTML elements before displaying them. The program logic is provided by the Template directives, and to connect the data of an application and the DOM, the binding markup is utilized. Data binding can be classified into two types:
- Event Binding: It binds events to an app. It is also used to respond to user input in the target environment by updating the data of the application.
- Property Binding: It passes data from the component class. It also facilitates the user to interpolate values that are estimated from the data of the application into the HTML.
Services and Dependency Injection:
For data or logic that isn’t associated with a specific view, and is required to share across components, a service class is created by the developers in Angular 7. To make lean and effective component classes, the Dependency Injection (DI) is used. DI simply renders the tasks like fetching data from the server, validating user input, or logging directly to the console; to services.
The router is a NgModule in Angular 7. It renders a service to facilitate the developers to determine a navigation path among the varied application states and to see hierarchies in their app. The router and the navigation of a browser work in the same way.
- The browser navigates to the corresponding page on entering a URL in the address bar.
- The browser navigates to a new page on clicking the link on a page.
- The browser navigates backwards or forwards according to the user’s seen history pages on clicking the browser’s back or forward buttons.
Working of a Router:
Instead of the pages, the URL-like paths are mapped to views by the router. The router intercepts the behavior of the browser, whenever a user acts. It thus shows or hides the view hierarchies. The router lazy-load the module on request, in case the router notices that the current application state needs distinct functionality and the module that sets it hasn’t been loaded. A link URL is interpreted by the router as per the view navigation rules of the app and the data state. When the user clicks a button or selects from a dropbox, the developer can navigate to new views. The developer can also navigate to new views in response to some other stimulus from any source. The activity in the browser’s history is logged by the router for the efficient working of the back and forward buttons. The navigation paths are associated with the components to define navigation rules. A URL-like syntax is used by a path to integrating the program data. It is done in the same way the integration of the views with the program data by the template syntax. The program logic can then be applied to decide which views to display or to hide, in response to the user input and developer’s own access rules.