Monday, 25 July 2022 17:45

Designing Angular Apps

Angular architecture Angular architecture pixabay

In this article, I'll discuss some of the best practices for designing Angular apps, including the Angular Document Object Model (DOM). This is a model that treats XML or HTML documents as trees, and then updates that entire tree structure to create a new view.

In addition, I'll cover Angular's use of TypeScript, a set of JavaScript types that makes it easier to understand. Though it's not necessary to use TypeScript in your Angular application, it does provide better syntactic structure and makes the codebase more readable.

Angular Architecture Patterns

Angular modules are a collection of interrelated components, directives, pipes, and services that define an angular application. These components are similar to pieces of a jigsaw puzzle, where each piece is needed to see the entire picture. These modules are the foundation of Angular applications, and they should be present in any application. This article focuses on the App Module, one of the most important Angular architecture patterns.

Components are the basic building blocks of an Angular application. Each component consists of four major constituents: a TypeScript class, HTML template, and optional CSS styles. Each component is used to define the views. The views are used to display various types of data, such as a list of heroes, application root, and hero editor. The components can be grouped into views using templates and other types of metadata.

Angular Login

When a user logs in to your app, he or she is presented with a navigation bar. The navigation bar contains links to the user's profile and to other content. The user can also log out and see the user's previous activity. The app component defines the root tag of the app. The currentUser property contains logic for when to show and hide these links. When the user logs out, the app component calls the logout() method and sends them back to the login page.

Angular user login is a fundamental part of any web application. It allows developers to authenticate users, authorize them, and protect routes and API requests. Here's how to implement a user login in your Angular application:

Angular Interceptor

In the simplest form, an Angular interceptor is a JSX function that modifies the request's HTTP headers. This function is used to handle authentication and authorization of HTTP requests. The Angular interceptor is applied in the order in which module providers are added to a request. It's important to note that an interceptor can't change the order of the request or remove it altogether. Therefore, you must build the capability of dynamically adding or removing an interceptor yourself.

Unlike a normal method, an Angular interceptor can handle both incoming and outgoing requests. It can also handle errors and provide retry logic. It can also time the delay between the request and response. The following code snippet illustrates a typical interceptor. You can find more information about this function in the Angular documentation. However, it's essential to have a basic understanding of how this type of interceptor works before implementing it in your own application.

How does interceptor work?

If you're not sure what an interceptor is, it is a component that handles incoming and outgoing requests. In many cases, an interceptor will handle authentication, adding authorization headers to the http request. It can also transform the request and return it without passing it to the next interceptor. In general, you should use interceptors sparingly, however. Let's look at how they work.

The interceptor is a component defined in the Angular HTTP module. These services are injected into the HttpClientModule, where they act as middleware between your application's code and the client. HTTP requests are passed through a chain of interceptors, with each one altering the request in some way. This makes interceptors an extremely useful component when handling authentication and error handling.

Custom Header Interceptor

When using Angular's multi-provider model, you can add your own HTTP header interceptor to your Angular app. These interceptors are applied in the order of module providers. A common use for interceptors is handling authentication. They change the http request, adding authorization headers. However, they may also be used to implement other common logic. You can learn more about the two types of interceptors and how to add them in your own code.

HTTP Interceptors are extremely complex to implement, and a new Angular 7 feature introduces observable HTTP event streams. By adding a small delay to an AJAX request, you can increase the time taken for HTML templates to be fetched. These unintended consequences violate the principle of least surprise. To solve this problem, you'll want to build your interceptor with capabilities that let you configure the behavior and enable it dynamically.

 
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