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AngularJS Hosting Europe - HostForLIFE.eu :: Error handling in Angular

clock January 20, 2025 06:34 by author Peter

In order to guarantee a seamless user experience and facilitate debugging, Angular error management entails recording and controlling errors. Angular comes with a number of built-in tools and methods for methodically managing faults.


1. Managing Errors in HTTP

The HttpClient and the catchError operator from RxJS can be used to manage errors in HTTP requests.

For instance
import { Injectable } from '@angular/core';
import { HttpClient, HttpErrorResponse } from '@angular/common/http';
import { catchError, throwError } from 'rxjs';

@Injectable({
  providedIn: 'root',
})
export class DataService {
  private apiUrl = 'https://api.example.com/data';

  constructor(private http: HttpClient) {}

  getData() {
    return this.http.get(this.apiUrl).pipe(
      catchError(this.handleError)
    );
  }

  private handleError(error: HttpErrorResponse) {
    if (error.error instanceof ErrorEvent) {
      // Client-side error
      console.error('Client-side error:', error.error.message);
    } else {
      // Server-side error
      console.error(`Server-side error: ${error.status} - ${error.message}`);
    }
    return throwError(() => new Error('Something went wrong; please try again later.'));
  }
}


catchError: Intercepts errors and allows custom handling.
throwError: Re-throws the error after handling it for further processing.

2. Global Error Handling
Angular provides a way to handle application-wide errors using the ErrorHandler service.

Custom Global Error Handler.
Create a custom error handler.
import { ErrorHandler, Injectable, NgZone } from '@angular/core';

  @Injectable()
  export class GlobalErrorHandler implements ErrorHandler {
    constructor(private ngZone: NgZone) {}

    handleError(error: any): void {
      // Log the error to the console or a logging service
      console.error('Global Error:', error);

      // Notify the user (e.g., using a toast or modal)
      this.ngZone.run(() => {
        alert('An unexpected error occurred.');
      });
    }
  }
   

Register the error handler in AppModule.
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import { GlobalErrorHandler } from './global-error-handler';

@NgModule({
  declarations: [AppComponent],
  imports: [BrowserModule],
  providers: [{ provide: ErrorHandler, useClass: GlobalErrorHandler }],
  bootstrap: [AppComponent]
})
export class AppModule {}

The service will be used throughout the entire application to catch logs.

3. Error Interceptors
Use an HTTP interceptor to handle errors globally for all HTTP requests.

Example

Create an HTTP interceptor.
  import { Injectable } from '@angular/core';
  import { HttpInterceptor, HttpRequest, HttpHandler, HttpErrorResponse } from '@angular/common/http';
  import { catchError, throwError } from 'rxjs';

  @Injectable()
  export class ErrorInterceptor implements HttpInterceptor {
    intercept(req: HttpRequest<any>, next: HttpHandler) {
      return next.handle(req).pipe(
        catchError((error: HttpErrorResponse) => {
          // Handle different error types
          if (error.status === 404) {
            console.error('Not Found:', error.message);
          } else if (error.status === 500) {
            console.error('Server Error:', error.message);
          }

          // Optionally, rethrow the error
          return throwError(() => new Error('An error occurred. Please try again later.'));
        })
      );
    }
  }
   

Register the interceptor in AppModule.
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';
import { AppComponent } from './app.component';
import { ErrorInterceptor } from './error-interceptor';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    HttpClientModule
  ],
  providers: [
    {
      provide: HTTP_INTERCEPTORS,
      useClass: ErrorInterceptor,
      multi: true
    }
  ],
  bootstrap: [
    AppComponent
  ]
})
export class AppModule {}

4. Using Angular Guards for Route Error Handling
Angular guards can protect routes and handle access-related errors.
import { Injectable } from '@angular/core';
import { CanActivate, Router } from '@angular/router';

@Injectable({
  providedIn: 'root',
})
export class AuthGuard implements CanActivate {
  constructor(private router: Router) {}

  canActivate(): boolean {
    const isAuthenticated = false; // Replace with actual authentication logic
    if (!isAuthenticated) {
      alert('You are not authorized to access this page.');
      this.router.navigate(['/login']);
      return false;
    }
    return true;
  }
}


5. Error Display in the UI
Display user-friendly error messages in the UI using Angular components.

Example
Create an error message component.
import { Component, Input } from '@angular/core';

@Component({
  selector: 'app-error-message',
  template: `
    <div *ngIf="errorMessage" class="error">
      {{ errorMessage }}
    </div>
  `,
  styles: [
    `
      .error {
        color: red;
      }
    `,
  ],
})
export class ErrorMessageComponent {
  @Input() errorMessage: string | null = null;
}



Use the component.
<app-error-message [errorMessage]="error"></app-error-message>

6. RxJS Error Handling Strategies
    Retry Failed Requests.
    import { retry } from 'rxjs';

    this.http.get(this.apiUrl).pipe(
      retry(3), // Retry up to 3 times
      catchError(this.handleError)
    );

Fallback Data.
this.http.get(this.apiUrl).pipe(
  catchError(() => of([])) // Return fallback data on error
);


7. Logging Errors
Use external services like Sentry, LogRocket, or custom logging services to log errors.

Example
@Injectable({
  providedIn: 'root'
})
export class LoggingService {
  logError(message: string, stack: string) {
    // Send error logs to an external server
    console.log('Logging error:', message);
  }
}




AngularJS Hosting Europe - HostForLIFE.eu :: Using Pipes to Create Clear and Effective Angular Applications

clock January 8, 2025 06:45 by author Peter

The use of "pipes" is one of Angular's most potent tools for formatting and changing data inside templates. Developers can apply transformations like formatting dates, changing text cases, or even filtering data in an efficient and reusable way by using pipes, which offer a declarative mechanism to handle data before it is shown to the user.

Writing clean, manageable, and modular code for Angular applications requires an understanding of pipes. The main distinctions between pipes and functions will be discussed in this post, along with how to use built-in pipes and make your own custom pipes to increase Angular's functionality. You will have a firm grasp on how to integrate pipes into your Angular projects to improve user experience and expedite data presentation by the end of this tutorial.

What is an Angular Pipe?
In Angular, a pipe is a way to transform data before it is displayed in the user interface. Pipes can be used in templates to modify or format data without having to alter the original data.

Pipes are an Angular concept, not a TypeScript (TS) feature. They are a core part of Angular’s template syntax and are used to transform data in the view (template) layer of Angular applications.

Key Points about Pipes in Angular

  • Angular-Specific: Pipes are a built-in feature of the Angular framework designed to be used in Angular templates. They are not a native feature of JavaScript or TypeScript.
  • Purpose: Their primary function is to transform data in the template before it is displayed to the user. This transformation can include formatting dates, numbers, currencies, filtering arrays, or performing more complex data transformations.

Declarative Transformation: Pipes enable declarative transformation of data within the template, meaning that the logic for transforming data is cleanly abstracted away from the component’s TypeScript code.

You may be wondering why we should use Pipes when we can use functions.

Criteria Pipe Function
Purpose Data transformation in the template Business logic and calculations
Use case Formatting, filtering, sorting, etc. Complex or multi-step calculations
Performance Pure pipes are efficient for transforming data only when needed Functions can be less performant when used in templates (requires manual calls)
Reusability Highly reusable across templates Functions are reusable within the component or service
Asynchronous Handling Handles observables and promises with AsyncPipe Requires manual subscription logic or use of 'async' in templates
Complexity Best for simple, declarative transformations Best for complex or dynamic logic
When to use When transforming data for display in the template When performing business logic or side effects that don't belong in the template

Types of Pipes
There are two types of Pipes.
Pure Pipe (Default): A pure pipe will only re-run when its input value changes.
    @Pipe({

      name: 'pureExample',

      pure: true // This is the default value, so you can omit this

    })

    export class PureExamplePipe implements PipeTransform {

      transform(value: any): any {

        console.log('Pure pipe executed');

        return value;

      }

    }


Impure Pipe: An impure pipe will re-run whenever Angular detects a change in the component’s state, even if the input value hasn’t changed.
@Pipe({
  name: 'impureExample',
  pure: false // Set to false to make it impure
})
export class ImpureExamplePipe implements PipeTransform {
  transform(value: any): any {
    console.log('Impure pipe executed');
    return value;
  }
}


In Angular, you can use in-built pipes or create your own.

In-built pipes

Angular provides some basic pipes that can be used.
It comes from the '@angular/common' package.

Some popular ones that can be helpful are:
CurrencyPipe, DatePipe, DecimalPipe, LowerCasePipe, UpperCasePipe and TitleCasePipe

How to use an in-built pipe?

In your ts file, define your variable. In our example, we will use the variable title.
title = 'app works!';

In your html, you can use the pipe as follows:
<h1> {{title | uppercase}} </h1>

The result is how the string title is displayed:

Note. The currency ‘USD’ is added in front because of the currency pipe, and only 10 characters are displayed because of the slide pipe.

Custom pipes

Run the command below to create a pipe file:
ng generate pipe <<pipe-name>>.

For example: ng generate pipe my-custom-pipe. Once executed, the two files below will be created

Open the file ‘my-custom-pipe.pipe.ts. You will see the following boilerplate code provided:
import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'myCustomPipe'
})
export class MyCustomPipePipe implements PipeTransform {
  transform(value: any, args?: any): any {
    return null;
  }
}


After the default class, you can create the function for your new pipe. In our case, we will create a pipe that will replace spaces in a hyphen. It is important to add the decorator ‘@Pipe’ before the class so that Angular knows what follows will be a pipe. Also, pass the name of the pipe as a parameter in the ‘@Pipe’ decorator. Also, when creating the class, implement ‘PipeTransform’. The resulting class will be as follows:
@Pipe({name: 'removeWhiteSpace'})
export class RemoveWhiteSpacePipe implements PipeTransform {
  transform(value: string): string {
    return value.replace(/\s+/g, '-');
  }
}


The resulting class will be as follows (the full code):
import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'myCustomPipe'
})
export class MyCustomPipePipe implements PipeTransform {


  transform(value: any, args?: any): any {
    return null;
  }
}

@Pipe({name: 'removeWhiteSpace'})
export class RemoveWhiteSpacePipe implements PipeTransform {
  transform(value: string): string {
    return value.replace(/\s+/g, '-');
  }
}


In the ts file of your component, create the variable that will hold the value that will be transformed
textWithSpaces = 'This is a text with a lot of spaces that will be transformed';

In the html file of your component, do the following:
<p>{{ textWithSpaces | removeWhiteSpace }}</p>

The result is the following:

Conclusion
An effective and potent method for formatting and transforming data in the templates of your application is to use angular pipes. Without having to code repetitious logic in your components, you can quickly manipulate data types like strings, dates, and numbers by utilizing built-in pipes. More freedom is provided by custom pipelines, which let you design modular, reusable, and maintainable transformation logic that is suited to your particular requirements.

Understanding the distinction between pipes and functions is key to leveraging their full potential. While functions provide a direct way to execute code, pipes offer a declarative approach to handle transformations directly within templates, improving readability and performance.

Whether you're working with Angular’s built-in pipes or creating custom ones, the ability to easily manipulate data in the view layer is a significant advantage in building dynamic and user-friendly applications. By mastering Angular pipes, you can keep your code clean, concise, and aligned with best practices, ultimately leading to more maintainable and scalable applications.

With the knowledge of how to use and create pipes, you’re now equipped to enhance your Angular applications with powerful data transformations, making your development experience more efficient and enjoyable.



AngularJS Hosting Europe - HostForLIFE.eu :: In VS Code by Debuggers for Chrome New

clock December 16, 2024 06:13 by author Peter

More than four years ago, on January 15, 2021, Debugger for Chrome wrote the post Debug Angular (1) in VS Code. With 208K readings, that article is really popular. This indicated that while Angular is a very popular tool for web development, it is difficult to persuade many developers to focus on its devugging technology. Although this article is a supplement to the original, I am aware that the Visual Studio Code Debugger for Chrome has been deprecated. We'll check if the original article is still relevant or valid.

Debug Angular in VS Code
Now the current VS Code is with v1.95.3. The VS Code Debugger for Chrome is deprecated:

However, user is introduced to use the JavaScript Debugger extension instead. Click the link, we can see that

this extension is already installed if you use VS Code or Visual Studio:

And furthermore,

Nightly Extension you may want to install our nightly build to get the latest fixes and features. The nightly build runs at 5PM PST on each day that there are changes. You can get Nightly extension from JavaScript Debugger (Nightly) - Visual Studio Marketplace, or search in VS Code extension for
@id:ms-vscode.js-debug-nightly

Debugging in VS Code

Actually, the debugging is the same way as we introduced in article, Debug Angular (1), In VS Code by Debugger for Chrome, we will not repeat the process, but given here the major points:

Configure the launch.json file --- choose the port as your app running

Run the app from the Angular CLI (very important, otherwise, the debugging will not work) by command.
Start to debug.



AngularJS Hosting Europe - HostForLIFE.eu :: Integration of Angular with Microservices

clock October 10, 2024 07:00 by author Peter

I'm a slack backend.net developer. I have some knowledge of.net technologies, however I'm not very knowledgeable with Angular, a frontend JavaScript framework. In order to enable external communication between the front-end and RESTful web API services, my manager instructed me to jot down certain typescript codes. You all know what would happen if I told him I didn't know how to do it. Anyhow, let's return to the primary topic. Please be aware that this is only intended for novice users who want to fire once and forget. Please don't hold me responsible. My knowledge of typescripts is rather limited.

Resolution and Schematic Design

  • I divided the entire assignment into four sections at first:
  • Examining the options in the app.
  • Setting up an environment depends on whether it's for production, QA, or development.
  • Establishing a connection with external RESTful web API services.
  • Requests to the services that include instructions or questions.

Basic knowledge - I guess you know it. So, in short.

  • Restful web API: it’s an interface for communication with two or more applications.
  • TypeScript: Compared to javaScript, It supports writing code with object-oriented concepts.
  • Singleton design pattern: It creates a single shared instance of the object.
  • Dependency injection design pattern: It is a style of object configuration in which objects are set by an external entity.

Explanation of each of the steps

  • Step 1: Read all the configuration at runtime from the appSettings.json file so that applications can use this data at runtime.
  • Step 2: Check the environment. Is it development, QA, or production? Set the environment settings data that you got from step 1.
  • Step 3: Create a base class for the service to get the API service, for instance. Design it using the concept of the singleton design pattern. Get the settings data from step 2.
  • Step 4: The main service class calls all the get/post/put/patch/delete required requests to the RESTful web API. Add the base class from step 3.
  • Step 5: Use the dependency Injection pattern to inject the dependent service. Inject the dependent service class into the component class. Call the required methods of the service from the component class. Use the class from step 4.

Implementation of each of the classes using typeScript in the Angular project

  • appsettings-json-reader package: Read all the data from the JSON file.
  • npm install appsettings-json-reader

Axios package: Promise-based API method called.
npm install axios --save

I guess you already know how to implement step1 & step2.

Implementing steps 3
Creating the base class using a command.
ng g class BaseApiClientService

import { Injectable } from "@angular/core";
import axios from "axios";
import { AppSettingsConfig } from "../../configuration/app-settings-config";

@Injectable()
export class BaseApiClientService {
  private appSettings!: AppSettingsConfig;
  private helloApiBaseUrl!: string;

  constructor() {
    // Holding configuration-data object.
    this.appSettings = new AppSettingsConfig();

    // Getting base URL of the Hello-API.
    this.helloApiBaseUrl = this.appSettings.apiEndPoint;
  }

  // Main API Instance.
  readonly HelloApiInstance = () => {
    return axios.create({
      baseURL: this.helloApiBaseUrl,
      timeout: 5000,
      headers: {
        Accept: 'application/json',
        cors: true,
        'Access-Control-Allow-Origin': '*',
        'Access-Control-Allow-Methods': 'GET, PUT, POST, DELETE, PATCH, OPTIONS',
      }
    });
  }
}


Implementing steps 4
Creating the service class using a command.
ng g service Hello-Api-Service

import { Injectable } from '@angular/core';
import { AxiosInstance } from 'axios';
import { ConstApiSubPathConfig } from '../../configuration/const-api-sub-path-config';
import { BaseApiClientService } from './base-api-client-service';

@Injectable({
  providedIn: 'root'
})
export class HelloAPIServiceService {
  readonly helloWebApiInstance: AxiosInstance;

  constructor(private baseClient: BaseApiClientService)
  {
    this.helloWebApiInstance = this.baseClient.HelloApiInstance();
  }

  GetHelloDataList(isActive:boolean) {
    //// It will add the pathSufix with the main base URL path.
    let pathSufix = '/' + ConstApiSubPathConfig.HelloApiSubDaListPathSufix;

    //// Get request:Returns the response.
    return this.helloWebApiInstance.get(pathSufix, {
      params: { IsActive: isActive }});
  }

  AddHelloMessage(helloMessageObj: any) {
    let pathSufix = '/' + ConstApiSubPathConfig.HelloApiSubPathSufix;

    //// Post request:Returns the response.
    return this.helloWebApiInstance.post(pathSufix, helloMessageObj);
  }
}

Implementing Steps 5
Creating the component class using a command.
ng g component HelloServiceGrid --module app

import { Component } from '@angular/core';
import { HelloAPIServiceService } from '../../../core/service/axios-service/hello-api-service.service';

@Component({
  selector: 'app-hello-service-grid',
  templateUrl: './hello-service-grid.component.html',
  styleUrls: ['./hello-service-grid.component.css']
})
export class HelloServiceGridComponent {
  constructor( private api: HelloAPIServiceService){  }
  getHelloDataList()
  {
      let isActive:boolean = true;
      this.api.GetHelloDataList(isActive)
      .then(response => {

        //// if status-code is success.
        if (response.status === 200) {
          /// Response Data from API.
          let result = response.data;

          //// Implement your logic with the data below:
        }
      }).catch(error => console.log('Error message =====> Sorry : ' + error.message));
  }
}


Don’t forget to check the App.module.ts file. Your components should be added to the declarations array, and your services should be added to the providers array.


I'll go over how to define environmental configurations and read configurations at runtime in the next section, which covers leveraging Azure DevOps CI/CD pipelines to deploy an Angular app to the Azure environment. Anyhow, I have to leave.



AngularJS Hosting Europe - HostForLIFE.eu :: Knowing Angular vs. React

clock August 19, 2024 10:05 by author Peter

React and Angular are two of the most widely used front-end frameworks for creating contemporary online apps. Both are supported by sizable groups and have distinct advantages, yet they serve varying needs and tastes. We'll go over the main distinctions between Angular and React in this post to assist you in choosing the right framework for your project.

Overview

  1. React
    • Developed by: Facebook
    • Initial Release: 2013
    • Type: JavaScript library for building user interfaces, primarily focused on rendering UI components.
    • Learning Curve: Moderate
    • Main Concept: React is centered around components and follows a unidirectional data flow.
  2. Angular
    • Developed by: Google
    • Initial Release: 2016 (as Angular 2, the complete rewrite of AngularJS)
    • Type: Full-fledged framework for building web applications.
    • Learning Curve: Steep
    • Main Concept: Angular is an opinionated framework that provides a comprehensive solution for building large-scale applications, including built-in features like routing, state management, and HTTP services.

Architecture

  1. React
    • Component-Based: React is all about components. Each piece of UI is a component that can manage its state and be reused throughout the application.
    • Virtual DOM: React uses a virtual DOM to optimize rendering performance. When the state of a component changes, React updates the virtual DOM and then efficiently updates the real DOM.
    • Flexibility: React offers flexibility by allowing developers to choose their own libraries for routing, state management, and other needs. This makes React a "view library" rather than a full-fledged framework.
  2. Angular
    • MVC Architecture: Angular follows the Model-View-Controller (MVC) pattern, which helps in separating the concerns of data (Model), UI (View), and logic (Controller).
    • Real DOM: Unlike React, Angular directly interacts with the real DOM, which can impact performance in complex applications. However, Angular mitigates this with its change detection mechanism.
    • Built-In Features: Angular comes with a range of built-in features like form validation, HTTP client, routing, and RxJS for reactive programming. This makes Angular a complete solution for building applications without relying on external libraries.

Performance

  1. React
    • Virtual DOM: React’s virtual DOM significantly improves performance by minimizing the number of direct manipulations to the real DOM.
    • Component Reusability: React’s component-based architecture promotes reusability, which can lead to better performance in large applications.
    • Bundle Size: React itself is relatively lightweight, but depending on the additional libraries you use, the bundle size can grow.
  2. Angular
    • Change Detection: Angular’s change detection mechanism can sometimes lead to performance bottlenecks in large applications, but it also provides tools like OnPush strategy and NgZone to optimize performance.
    • Ahead-of-Time (AOT) Compilation: Angular’s AOT compilation improves performance by compiling the application during the build process, reducing the load time.
    • Built-In Features: While Angular’s rich feature set can impact performance, the framework’s ability to optimize these features mitigates the impact.

Learning Curve

  1. React
    • JSX: React uses JSX, a syntax extension that allows you to write HTML within JavaScript. While some developers find JSX intuitive, others might find it challenging initially.
    • Flexibility: React’s flexibility means you need to learn how to integrate and use various libraries for routing, state management, etc., which can be both an advantage and a challenge.
    • Documentation and Community: React has extensive documentation and a large community, making it easier to find resources, tutorials, and third-party libraries.
  2. Angular
    • Steep Learning Curve: Angular has a steeper learning curve due to its complexity and the number of built-in features you need to understand.
    • TypeScript: Angular is built with TypeScript, a statically typed superset of JavaScript. While this adds benefits like better tooling and error checking, it also requires learning TypeScript if you’re not already familiar with it.
    • Comprehensive Framework: Angular’s opinionated nature means that once you learn the Angular way of doing things, you have a powerful set of tools at your disposal.

Ecosystem and Community

  1. React
    • Ecosystem: React has a rich ecosystem with numerous libraries for state management (Redux, MobX), routing (React Router), and more. The flexibility to choose different tools gives developers more control over their stack.
    • Community: React has a large and active community, contributing to a vast array of plugins, tools, and resources.
  2. Angular
    • Ecosystem: Angular has a more integrated ecosystem. Many features that require third-party libraries in React are built into Angular, such as routing, HTTP services, and form handling.
    • Community: Angular also has a large community, but it is more centralized around the official Angular resources, documentation, and Google-backed initiatives.

Use Case
React

  1. When to Use React
    • You need flexibility in choosing libraries and tools.
    • You prefer a simple, component-based architecture.
    • You are building a project where performance and simplicity are key.
  2. Popular Use Cases
    • Single-page applications (SPAs)
    • Static sites with dynamic components
    • Dashboards and data visualization tools

Angular

  1. When to Use Angular
    • You are building a large-scale, enterprise-level application.
    • You need a framework with a comprehensive set of tools and built-in features.
    • You prefer an opinionated framework that guides architectural decisions.
  2. Popular Use Cases
    • Complex, enterprise-level applications
    • Applications requiring robust form handling and validation
    • Real-time applications with complex state management

Conclusion
The skills of your team and the needs of your project will determine which of React and Angular is best. React is an excellent option for projects where you want more control over the architecture because of its simplicity and versatility. In contrast, Angular offers a feature-rich, opinionated framework right out of the box, making it perfect for enterprise-level apps.

Both Angular and React are effective front-end development tools, and knowing the advantages and disadvantages of each will help you choose wisely for your upcoming project.




AngularJS Hosting Europe - HostForLIFE.eu :: Study Angular's Component Routing

clock August 14, 2024 07:19 by author Peter

In Angular, component routing is usually done via the Router service. This allows you to call or go to a component from another component. Here's how you can make this happen. In the Router Module, define routes. The first step is to configure your routes in your AppRoutingModule (or any other defined routing module). Describe the pathways and the matching parts.


import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { ComponentA } from './component-a/component-a.component';
import { ComponentB } from './component-b/component-b.component';

const routes: Routes = [
  { path: 'component-a', component: ComponentA },
  { path: 'component-b', component: ComponentB },
  // Add more routes as needed
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

Use RouterLink in Templates
You can navigate to another component using the RouterLink directive in your template (HTML) of the first component.
<!-- component-a.component.html -->
<a [routerLink]="['/component-b']">Go to Component B</a>

Navigate Programmatically Using the Router
You can also navigate programmatically using the Angular Router in your component's TypeScript file.
import { Component } from '@angular/core';
import { Router } from '@angular/router';

@Component({
  selector: 'app-component-a',
  templateUrl: './component-a.component.html',
  styleUrls: ['./component-a.component.css']
})
export class ComponentA {

  constructor(private router: Router) { }

  goToComponentB() {
    this.router.navigate(['/component-b']);
  }
}


In HTML template
<!-- component-a.component.html -->
<button (click)="goToComponentB()">Go to Component B</button>


Outlet to Render Routed Components
Ensure you have a <router-outlet></router-outlet> in your main HTML template (e.g., app.component.html) where the routed components will be displayed.
<!-- app.component.html -->
<router-outlet></router-outlet>


Lazy Loading (Optional)
If you want to load a module lazily, define your route like this.
const routes: Routes = [
  {
    path: 'component-b',
    loadChildren: () =>
      import('./component-b/component-b.module')
        .then(m => m.ComponentBModule)
  }
];


Summary

  • RouterLink: For navigation within the template.
  • Router.navigate: For programmatic navigation within the component's TypeScript file.
  • Router Outlet: Acts as a placeholder in the template where routed components are displayed.


This setup allows you to call or navigate between components effectively in Angular.



AngularJS Hosting Europe - HostForLIFE.eu :: Enhancing Angular Efficiency With The @defer Directive

clock August 6, 2024 06:57 by author Peter

Increasing the speed and smoothness of an application requires performance tuning. To aid in this, Angular, a well-liked framework for creating online applications, has introduced the @defer directive. Both load times and user experience are enhanced. We'll explain the @defer directive, its operation, and how you can use it to improve your Angular apps in this blog post.

@defer: What is it?

Using an Angular condition, the @defer directive allows you to load specific portions of a template only when needed. This can improve the efficiency of your program by only rendering components when required. For instance, it can load and display material only after the user presses a button or until a certain portion of the screen is visible. In this manner, your software loads faster and more effectively because it just loads what is needed.

Syntax
@defer () {
} @placeholder () {
} @loading () {
} @error {
}


@defer Directive
This is used to delay the loading of a template fragment until certain conditions are met.
on <trigger>: Specifies an event that triggers the deferred loading. Here is one simple example of on viewport trigger

@defer (on viewport) {
  <component />
}

(on viewport) specifies that the deferred rendering should happen when the element comes into the viewport.

when <condition>: Defines the condition that needs to be true before the template is loaded.
prefetch on <trigger>: Optionally, you can prefetch the content based on a trigger.
prefetch when <condition>: Optionally, you can prefetch the content when a certain condition is true.

@placeholder Directive
This defines what should be shown while the deferred content is being loaded.

@loading Directive

This defines the content to be shown while the deferred content is actually loading.

@error Directive

This defines what should be shown if there's an error during the loading process.

In short, this syntax lets you control when different parts of your Angular template appear and what to show while you’re waiting, depending on different conditions and triggers.

Benefits of Using @defer directive

  • Faster Loading: By delaying less important content, your app loads quicker and feels smoother to use.
  • Better User Experience: Users see the key parts of your app right away, while the less important stuff loads in the background, so the app stays responsive.
  • Efficient Use of Resources: By waiting to display parts of your app that aren’t needed right away, you free up your browser’s resources, making everything run more smoothly.


Summary

The @defer directive in Angular helps make your app run better and faster. It allows you to delay loading some parts of your app until they're really needed. This way, your app stays quick and responsive, even if it has a lot of data or complex tasks. Using @defer can make your app perform better and provide a smoother experience for users.

Please let me know in the comments area if you have any questions.



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