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AngularJS Hosting Europe - HostForLIFE.eu :: Show/Hide Div on Click of Radio Button using Angular and Bootstrap

clock February 19, 2024 06:58 by author Peter

This article will teach us how to use the ngModel directive in the Angular application to show and hide div when the radio button is clicked. Additionally, we study how to construct the Bootstrap Toasts component in Angular. The process of creating the radio buttons, binding the div to radio buttons, and hiding and showing after selection is template-driven.


Note: As stated below, please read my prior essay on Angular applications before beginning this session.

1. In the App Module, import the FormsModule
To work with angular forms, import the forms module (FormsModule) and add the imports: [] array section. Look for the code below in the file src/app/app.module.ts.

import { BrowserModule, Title } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule
  ],
  providers: [Title],
  bootstrap: [AppComponent]
})
export class AppModule { }

Step 2: Modify the HTML template

The radio buttons are defined here, along with the ngModel directive and the value it receives. The checked state and values are defined in a similar manner. Initially concealed, four divisions become visible when clicking the radio button. Look for the code in the file src/app/app.component.html.

<div class="card bg-warning text-white">
<div class="card-body">
  <h2>Angular Radio Button Click For Show or Hide Div</h2>
    <input [value]="1" [(ngModel)]="sh" name="sh" type="radio" [checked]="isChecked" /> Peter
  &nbsp;
    <input [value]="0" [(ngModel)]="sh" name="sh" type="radio" [checked]="!isChecked" /> Scott
  <div class="text-center card bg-success text-white" *ngIf="sh == 1">Satyaprakash</div>
  <div class="text-center card bg-danger text-white" *ngIf="sh == 0">Kulu</div>
</div>
</div>

<div class="toast show" style="position: absolute; top: 0; right: 0; color: red;font-weight:900;font-size:larger;" *ngIf="sh == 1">
  <div class="toast-header">
    You Selected
    <button type="button" class="btn-close" data-bs-dismiss="toast"></button>
  </div>
  <div class="toast-body">
    Peter
  </div>
</div>

<div class="toast show" style="position: absolute; top: 0; right: 0;color: red;font-weight:900;font-size:larger;" *ngIf="sh == 0">
  <div class="toast-header">
    You Selected
    <button type="button" class="btn-close" data-bs-dismiss="toast"></button>
  </div>
  <div class="toast-body">
    Kulu
  </div>
</div>

Radio buttons are used in this implementation of the ngModel directive.
<input [value]="1" [(ngModel)]="sh" name="sh" type="radio" [checked]="isChecked" /> Peter
  &nbsp;
<input [value]="0" [(ngModel)]="sh" name="sh" type="radio" [checked]="!isChecked" /> Scott

For normal Div show or hide,
<div class="text-center card bg-success text-white" *ngIf="sh == 1">Peter</div>
<div class="text-center card bg-danger text-white" *ngIf="sh == 0">Scott</div>


For Bootstrap Toast component,
<div class="toast show" style="position: absolute; top: 0; right: 0; color: red;font-weight:900;font-size:larger;" *ngIf="sh == 1">
  <div class="toast-header">
    You Selected
    <button type="button" class="btn-close" data-bs-dismiss="toast"></button>
  </div>
  <div class="toast-body">
    Peter
  </div>
</div>

<div class="toast show" style="position: absolute; top: 0; right: 0;color: red;font-weight:900;font-size:larger;" *ngIf="sh == 0">
  <div class="toast-header">
    You Selected
    <button type="button" class="btn-close" data-bs-dismiss="toast"></button>
  </div>
  <div class="toast-body">
    Scott
  </div>
</div>

Step 3. Update TypeScript Template
Here we set the isChecked variable with false value. Make sure to define another variable by the name of “sh” in angular TypeScript component. Add the code in src/app/app.component.ts file.
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  isChecked: boolean = false;
  sh: any;
  constructor() {
  }
}


Step 4. Add Bootstrap to make page responsive
Add code in index.html file,
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Title Service Example</title>
  <base href="/">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="icon" type="image/x-icon" href="favicon.ico">
  <link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet">
  <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/js/bootstrap.bundle.min.js"></script>
</head>
<body>
  <app-root></app-root>
</body>
</html>


Output
Here, we run the command (ng serve) to start the angular app server.  The result is shown on first time page load:

Then it performs hide and show HTML div on radio buttons click in angular application with the help of ngModel directive.



AngularJS Hosting Europe - HostForLIFE.eu :: Angular Content Projection: Reusability and Flexibility of the UI

clock February 1, 2024 08:13 by author Peter

The robust front-end framework Angular offers developers a number of tools to create dynamic and manageable user interfaces. Content projection is one such feature that greatly enhances UI flexibility and reusability. Through the dynamic injection of content into predetermined slots inside a component's template, content projection enables developers to design components that are both adaptable and reusable.


Comprehending Content Projection

A feature in Angular called content projection, or transclusion, allows content from a parent component to be inserted into a specific area of a child component. This method facilitates the creation of adaptable and adjustable user interfaces and encourages component reuse.

Content Projection's Advantages
Component Reusability: Content projection enables programmers to design components that may be applied to various areas of an application at different times. Content can be projected into designated slots to increase component versatility and adaptability to a range of use scenarios.
Simplified API: Rather than requiring intricate setups, components may expose a simplified API that accepts content as input. This improves code maintainability by making the components simpler for developers to use and comprehend.
Consistent Style and Layout: Content projection aids in preserving uniform styling and layout throughout an application's many sections. Components with specified slots can be designed by developers to guarantee that the content projection follows a consistent format.
Improved Concern Separation: Content projection promotes a distinct division of responsibilities between the parent and child components. Child components manage the content display, allowing parents to concentrate on business logic, thus fostering a modular and maintainable codebase.

Practical Use Case
Think of a basic card component that can show text, photos, or even bespoke components, among other kinds of information. We may construct a reusable card component that can adjust to various content kinds by using content projection.

card.component.ts

import { Component } from '@angular/core';

@Component({
  selector: 'app-card',
  standalone: true,
  imports: [],
  template: `
    <div class="card">
      <div class="card-header">
        <ng-content select="[card-header]"></ng-content>
      </div>
      <div class="card-body">
        <ng-content select="[card-body]"></ng-content>
      </div>
      <div class="card-footer">
        <ng-content select="[card-footer]"></ng-content>
      </div>
    </div>
  `,
  styles: [
    '.card { border: 1px solid #ddd; border-radius: 8px; overflow: hidden; margin: 16px; }',
    '.card-header, .card-footer { background-color: #f0f0f0; padding: 8px; }',
    '.card-body { padding: 16px; }',
  ],
})
export class CardComponent {}


In this example, the CardComponent defines three slots: card-header, card-body, and card-footer. The content projected into these slots will be rendered within the corresponding sections of the card.

app.component.ts
import { CommonModule } from '@angular/common';
import { Component } from '@angular/core';
import { CardComponent } from './card/card.component';

@Component({
  selector: 'app-root',
  standalone: true,
  imports: [CommonModule, CardComponent],
  template: `
    <app-card>
      <div card-header>
        <h2>Angular is awesome</h2>
      </div>
      <div card-body>
        <p>Lets have a fun with it</p>
      </div>
      <div card-footer>
        <button>Read More</button>
      </div>
    </app-card>

    <app-card>
      <div card-header>
        <h2>Product Information</h2>
      </div>
      <div card-body>
        <img
          src="https://cdn-images-1.medium.com/v2/resize:fit:184/1*[email protected]"
          alt="Product Image"
          style="max-width: 100%"
        />
        <ul>
          <li>Feature 1</li>
          <li>Feature 2</li>
          <li>Feature 3</li>
        </ul>
      </div>
      <div card-footer>
        <button>Add to Cart</button>
      </div>
    </app-card>
  `,
})
export class AppComponent {}



AngularJS Hosting Europe - HostForLIFE.eu :: Optimizing Templates for Angular

clock January 19, 2024 09:28 by author Peter

Immutable Objects: When using OnPush, it's beneficial to work with immutable objects. If you need to modify data, create a new object or array instead of modifying the existing one. This helps Angular recognize changes more efficiently.
this.data = [...this.data, newElement]; // Using the spread operator for arrays

Input Properties: Ensure that your component's input properties are used correctly. When an input property changes, Angular triggers change detection for components using the OnPush strategy. If you're working with complex data structures, consider using @Input setters to handle changes.
import { Component, Input, ChangeDetectionStrategy } from '@angular/core';

@Component({
  selector: 'app-item',
  templateUrl: 'item.component.html',
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class ItemComponent {
  private _data: any;

  @Input()
  set data(value: any) {
    this._data = value;
    // handle changes if needed
  }

  get data(): any {
    return this._data;
  }
}


Event Handling: Be cautious with event handling. When using OnPush, events outside of Angular's knowledge (e.g., events from third-party libraries) may not trigger change detection automatically. Use ChangeDetectorRef to manually mark the component for check.
import { Component, ChangeDetectionStrategy, ChangeDetectorRef } from '@angular/core';

@Component({
  selector: 'app-example',
  templateUrl: 'example.component.html',
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class ExampleComponent {
  constructor(private cdr: ChangeDetectorRef) {}

  // Trigger change detection manually
  handleExternalEvent() {
    this.cdr.markForCheck();
  }
}


By using the OnPush change detection strategy and following these best practices, you can make your Angular application more efficient and responsive, especially in scenarios where components have a limited set of inputs or depend on immutable data.

2. Limit ngIf and ngFor in the Template

Limiting the use of ngIf and ngFor directives in your Angular templates is crucial for optimizing performance, as excessive use can lead to unnecessary rendering and affect the efficiency of change detection. Here are some best practices to follow:

  • Minimize ngIf and ngFor Nesting: Avoid deep nesting of ngIf and ngFor directives within your templates. The deeper the nesting, the more complex the change detection process becomes. Try to flatten your template structure when possible.
  • Filter Data Before Rendering: Instead of using ngFor to loop through all items and then applying conditions using ngIf, consider filtering your data in the component before rendering. This can reduce the number of elements in the template and improve rendering performance.

    <!-- Avoid -->
    <div *ngFor="let item of items" *ngIf="item.isValid">
      <!-- content -->
    </div>

    <!-- Prefer -->
    <div *ngFor="let item of validItems">
      <!-- content -->
    </div>


Use TrackBy with ngFor: When using ngFor, always provide a trackBy function to help Angular identify which items have changed. This can significantly improve the performance of rendering lists.
    <div *ngFor="let item of items; trackBy: trackByFn">
      <!-- content -->
    </div>


trackByFn(index, item) {
  return item.id; // Use a unique identifier
}


Avoid Excessive Use of Structural Directives: Be mindful of using too many structural directives (ngIf, ngFor, etc.) within a single template. Each structural directive introduces a potential change detection cycle, and having many of them can impact performance.

Lazy Load Components with ngIf: If you have complex or resource-intensive components, consider lazy-loading them using the ngIf directive. This way, the components will only be instantiated when they are needed.
<ng-container *ngIf="showComponent">
  <app-lazy-loaded-component></app-lazy-loaded-component>
</ng-container>


  • Paginate Large Lists: If dealing with large datasets, consider implementing pagination or virtual scrolling to load and render only the visible portion of the data. This can significantly improve the initial rendering time.
  • Profile and Optimize: Use Angular's built-in tools like Augury or browser developer tools to profile your application's performance. Identify components with heavy rendering and optimize accordingly.

3.  Lazy Loading Images
Lazy loading images is a technique that defers the loading of non-critical images until they are about to be displayed on the user's screen. This can significantly improve the initial page load time, especially for pages with a large number of images. Angular provides several ways to implement lazy loading of images. Here's a common approach:

Native Lazy Loading (HTML loading attribute): The HTML standard has introduced a loading attribute for the <img> element, which allows you to set the loading behavior of an image. The values can be "eager" (default), "lazy", or "auto". Setting it to "lazy" will enable lazy loading.
    <img src="image.jpg" alt="Description" loading="lazy">

The browser will then decide when to load the image based on its visibility in the viewport.

Angular Directives for Lazy Loading: You can use Angular directives for more control over lazy loading, especially if you need to perform custom actions when an image is loaded or when it enters the viewport.

a. Intersection Observer: Use the Intersection Observer API to detect when an element (such as an image) enters the viewport. Angular provides a directive named ng-lazyload-image that simplifies the integration with Intersection Observer.
npm install ng-lazyload-image

import { NgModule } from '@angular/core';
import { LazyLoadImageModule } from 'ng-lazyload-image';

@NgModule({
  imports: [LazyLoadImageModule],
  // ...
})
export class YourModule { }


<img [defaultImage]="'loading.gif'" [lazyLoad]="imagePath" alt="Description">

b. Custom Lazy Loading Directive: Alternatively, you can create a custom directive for lazy loading images. This approach provides more flexibility but requires a bit more code. You can use the Intersection Observer API or a library like lozad.js.
// lazy-load.directive.ts
import { Directive, ElementRef, Renderer2, OnInit } from '@angular/core';

@Directive({
  selector: '[appLazyLoad]'
})
export class LazyLoadDirective implements OnInit {

  constructor(private el: ElementRef, private renderer: Renderer2) { }

  ngOnInit() {
    const observer = new IntersectionObserver(entries => {
      entries.forEach(entry => {
        if (entry.isIntersecting) {
          this.loadImage();
          observer.unobserve(entry.target);
        }
      });
    });

    observer.observe(this.el.nativeElement);
  }

  private loadImage() {
    const imgSrc = this.el.nativeElement.getAttribute('data-src');
    if (imgSrc) {
      this.renderer.setAttribute(this.el.nativeElement, 'src', imgSrc);
    }
  }
}


<img [appLazyLoad]="imagePath" data-src="loading.gif" alt="Description">

4. ng-container
Use the <ng-container> element to group elements without introducing additional elements to the DOM. It is a lightweight container that doesn't render as an HTML element.
<ng-container *ngIf="condition">
  <!-- content -->
</ng-container>


5. Avoid Heavy Computation in Templates
Keep your templates simple and avoid heavy computations or complex logic. If necessary, perform such operations in the component class before rendering.
Move Logic to the Component
Use Pure Pipes Judiciously
Memoization
NgIf and NgFor Directives

6. Use Angular Pipes Efficiently
Be cautious with Angular pipes, especially those that involve heavy computations. Pipes can have an impact on performance, so use them judiciously. Consider memoization techniques if a pipe's output is deterministic and costly.
// component.ts
export class MyComponent {
  heavyComputationResult: any;

  ngOnInit() {
    // Perform heavy computation here
    this.heavyComputationResult = /* result */;
  }
}


<!-- component.html -->
<div>{{ heavyComputationResult | formatData }}</div>


7. ngZone Awareness

Be aware of NgZone and its impact on change detection. If you're performing operations outside of Angular (e.g., third-party libraries or asynchronous operations), you may need to use NgZone.run to ensure that change detection is triggered appropriately.

8. Production Build
Always build your application for production using AOT compilation. This helps in optimizing and minifying the code for better performance.
ng build --prod

By applying these optimization techniques, you can enhance the performance of your Angular templates and create a more responsive user experience.

Improving the performance of your Angular application requires optimizing Angular templates. To maximize Angular templates, consider the following advice and best practices:

1. Apply Change Detection using OnPush
Implementing Angular's OnPush change detection approach can greatly enhance your application's performance. Angular is instructed by the OnPush strategy to only check for changes when an event within the component is triggered or when the input attributes of the component change. Reduced change detection cycles may arise from this, improving overall performance. This is how OnPush is used:1.

Configure a Change Detection Method: Set ChangeDetectionStrategy as the changeDetection property in your component decorator.OnPush:

import { Component, ChangeDetectionStrategy } from '@angular/core';

@Component({
  selector: 'app-example',
  templateUrl: 'example.component.html',
  changeDetection: ChangeDetectionStrategy.OnPush
})
export class ExampleComponent {
  // component logic
}



AngularJS Hosting Europe - HostForLIFE.eu :: Minification and Tree Shaking in Angular

clock January 15, 2024 07:26 by author Peter

Minification and tree shaking are two fundamental techniques used in Angular (and other web development frameworks) to streamline and optimize code for best performance. These methods assist in decreasing the size of your application, which is essential for improved user experience and quicker load times. Now let's examine each of these procedures in relation to Angular:

1. First off, what is minification?
Minification is the process of renaming variables to shorter names and eliminating characters from your code that aren't needed, including whitespace and comments. Your code files will download more quickly as a result of this smaller size. Typically, TypeScript is used to write Angular applications, and it is subsequently transpiled to JavaScript. The JavaScript code that results is subjected to the minification process.

This is how to make Angular's minification enabled.

A. Manufacturing Construct
To build your production application, you can use the build command provided by Angular CLI. The Angular CLI automatically applies minification when you build for production.

ng build --prod

This command generates a production-ready bundle with minified and optimized code.

B. The Terser Plugin
The Terser plugin, used for minification in Angular, provides with different configuration options. By including options in your angular.json file, you can alter the minification procedure.

"architect": {
  "build": {
    "options": {
      "optimization": true,
      "outputPath": "dist/my-app",
      "terserOptions": {
        "compress": {
          "pure_funcs": ["console.log"],
          "drop_console": true
        },
        "mangle": true
      }
    }
  }
}

The functions that are pure and can be safely removed are specified using the pure_funcs parameter in the example above. All console statements are eliminated using the drop_console option, and variable names are obscured by setting mangle to true.

C. Compiling Angular AOT (Ahead-of-Time)
There are two compilation modes for Angular applications: Just-In-Time (JIT) and AOT (Ahead-of-Time). For production builds, AOT compilation is recommended since it enables greater tree shaking and optimization. Smaller bundle sizes are the outcome of its compilation of Angular templates and components during the construction process.

In your tsconfig.json file, you can set AOT compilation to run automatically.

"angularCompilerOptions": {
  "fullTemplateTypeCheck": true,
  "strictInjectionParameters": true
}

2. What Is Shaking of Trees?
The practice of removing unused or dead code from your program is called tree shaking. It contributes to reducing the bundle size by removing any unnecessary modules or code.

A. Configuration of the Module
Make sure the arrangement of your Angular modules permits efficient tree shaking. Dependencies and boundaries between modules should be obvious. To make the process of removing useless code easier, stay away from needless inter-module dependencies.

B. Analysis of Static Data
Tree shaking is most effective when combined with static analysis, so stay away from runtime code or dynamic imports that make it difficult for the build tool to identify which portions of the code are being utilized.

C. Mode of Production
Like minification, production builds yield the best results from tree shaking. Tree shaking is enabled automatically by Angular CLI when you execute the production build with the --prod flag.

ng build --prod

2. What Is Shaking of Trees?
The practice of removing unused or dead code from your program is called tree shaking. It contributes to reducing the bundle size by removing any unnecessary modules or code.

A. Configuration of the Module

Make sure the arrangement of your Angular modules permits efficient tree shaking. Dependencies and boundaries between modules should be obvious. To make the process of removing useless code easier, stay away from needless inter-module dependencies.

B. Analysis of Static Data
Tree shaking is most effective when combined with static analysis, so stay away from runtime code or dynamic imports that make it difficult for the build tool to identify which portions of the code are being utilized.


C. Mode of Production
Like minification, production builds yield the best results from tree shaking. Tree shaking is enabled automatically by Angular CLI when you execute the production build with the --prod flag.

ng build --prod

D. Angular Dependency Injection
The dependency injection system in Angular occasionally causes issues with tree shaking. Steer clear of injecting components or services that aren't needed in a certain module. This guarantees that the services that are not utilized are excluded from the final package.

E. Renderer of Angular Ivy
Angular Ivy, the new rendering engine introduced in Angular 9, adds enhancements to tree shaking. Better static analysis capabilities enable more efficient removal of dead code during the build process.

Configuring Webpack (for Advanced Users):
You can alter the webpack configuration that the Angular CLI uses if you require further control over the build process. This creates a webpack.config.js file in your project and involves ejecting the webpack configuration. Utilize this file to adjust code splitting and optimization, among other build process components.

In order to remove the webpack setup:
ng eject

Remember that ejecting is final and that you will be in charge of keeping the webpack settings updated.

In summary

In summary, minification and tree shaking are combined to optimize Angular apps. Achieving optimal performance requires configuring Terser's settings, turning on AOT compilation, properly structuring modules, and being aware of the limitations of tree shaking. Make sure the optimizations don't affect your application's functioning by conducting extensive testing.



AngularJS Hosting Europe - HostForLIFE.eu :: How To Configure AngularJS Environment Variables?

clock January 10, 2024 07:07 by author Peter

Setting environment variables in an AngularJS application happens at the configuration stage; this usually takes place in a separate file containing the configuration data. This is an illustration of how to set environment variables in an AngularJS application:

First Step
To save the environment variables, create a file in the root directory of your application, say config.js.

Step Two
Use the following code to define the environment variables in the file:

"use strict";
 angular.module('config', [])
.constant('ENV', {name:'development',tokenURL:'http://localhost:62511/token',apiURL:'http://localhost:62511/api',biUrl:'http://localhost:4200/',backgroundimage:'../images/backgroundimage.jpg',logo:'images/ogo.png'});


Step 3

Include the config.js file in your HTML file, just like any other JavaScript file:
<script src="scripts/index.config.js"></script>

Step 4

Inject the env constant in your AngularJS controllers, services, or directives to access the environment variables,

angular.module("myApp").controller("MyController", function($scope, env) {
    console.log(env.apiUrl);
    console.log(env.debugEnabled);
});
development: {
        options: {
            dest: '<%= yeoman.app %>/scripts/config.js'
        },
        constants: {
            ENV: {
                name: 'development',
                tokenURL: "http://localhost:62511/token",
                apiURL: "http://localhost:62511/api",
                biUrl: "http://localhost:4200/",
                backgroundimage: "../images/backgroundimage.jpg",
                logo: "images/logo.png",
            }
        }
    },
    qa: {
        options: {
            dest: '<%= yeoman.dist %>/scripts/config.js'
        },
        constants: {
            ENV: {
                name: 'qa',
                tokenURL: "https://qa.hostforlife.eu/token",
                apiURL: "https://qa.
hostforlife.eu/api",
                biUrl: "https://qa-dashboard.
hostforlife.eut/",
                backgroundimage: "../images/backgroundimage.jpg",
                logo: "images/logo.png",
            }
        }
    },

Grunt command to run the Application,

grunt build --qa



AngularJS Hosting Europe - HostForLIFE.eu :: Concat Operator in RxJS Library

clock January 3, 2024 06:51 by author Peter

The concat operator is used in RxJS (Reactive Extensions for JavaScript) to concatenate multiple observables together, sequentially, in the order that they are supplied. It makes ensuring that emissions from observables are processed sequentially and that they are subscribed to.


Set up RxJS

You can use npm to install RxJS if you haven't previously.

npm install rxjs

Import Concat and Any Other Essential Programs
To create observables, import the concat operator along with any additional functions or operators that you require. One way to build observables with values would be to utilize of.

import { concat, of } from 'rxjs';

Basic Syntax of RxJS
import { concat } from 'rxjs';
const resultObservable = concat(observable1, observable2, observable3, ...);

The concat function takes multiple observables as arguments, and it returns a new observable (resultObservable) that represents the concatenation of these observables.

Sequence of Action

  • In the order that they are passed to concat, observables are subscribed to.
  • Each observable's values are processed one after the other.

Awaiting Finalization

  • Concat waits for every observable to finish before proceeding to the following one.
  • Subsequent observables won't be subscribed to if an observable never completes, meaning it keeps emitting values forever.

Example
import { concat, of } from 'rxjs';

const observable1 = of(1, 2, 3);
const observable2 = of('A', 'B', 'C');

const resultObservable = concat(observable1, observable2);

resultObservable.subscribe(value => console.log(value));

Output
1 2 3 A B C

In this example, observable1 emits values 1, 2, and 3, and then observable2 emits values 'A', 'B', and 'C'. The concat operator ensures that the values are emitted in the specified order.

Use Cases

concat is useful when you want to ensure a sequential execution of observables.
It's commonly used when dealing with observables that represent asynchronous operations, and you want to perform these operations one after the other.

Error Handling
If any observable in the sequence throws an error, concat will stop processing the sequence, and the error will be propagated to the subscriber.

The concat operator in RxJS is a powerful tool for managing the sequential execution of observables, providing a clear order of operations and waiting for each observable to complete before moving on to the next one.



AngularJS Hosting Europe - HostForLIFE.eu :: Autofocus Directive in Angular

clock December 20, 2023 05:50 by author Peter

We will discover how to create a custom autofocus directive in an Angular application in this tutorial.


Required conditions
Basic familiarity with Angular 2 or later; installation of Node and NPM; Visual Studio Code; Bootstrap (Optional)

Make an Angular Project
The command to create an Angular project is as follows.
ng new angapp

Now install Bootstrap by using the following command,
npm install bootstrap --save

Now open the styles.css file and add Bootstrap file reference. To add a reference in the styles.css file add this line.
@import '~bootstrap/dist/css/bootstrap.min.css';


Create  Directive
Create  a new directive using the Angular CLI command
ng generate directive autofocus

Now open autofocus.directive.ts file and add following code
import { Directive, ElementRef, AfterViewInit } from '@angular/core';

@Directive({
  selector: '[Autofocus]'
})
export class AutofocusDirective implements AfterViewInit {
  constructor(private el: ElementRef) {}

  ngAfterViewInit() {
    this.el.nativeElement.focus();
  }
}


Now open app.component.html file and add the following code.
<div class="container" style="margin-top:10px;margin-bottom: 24px;">
  <div class="col-sm-12 btn btn-info">
    Autofocus Directive in Angular Application
  </div>
</div>
<div class="container">
  <input type="text" class="form-control" placeholder="Auto Focused Textbox" Autofocus />
</div>


Now open app.module.ts and following code
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { AutofocusDirective } from './autofocus.directive';


@NgModule({
  declarations: [
    AppComponent, AutofocusDirective
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent],

})
export class AppModule { }


Now run the application using npm start and check the result.

We discovered how to make a personalized autofocus directive in an Angular application by reading this post.



AngularJS Hosting Europe - HostForLIFE.eu :: Angular Reverse String Pipe

clock December 15, 2023 06:50 by author Peter

We will discover how to build a pipe in an Angular application to reverse a string in this tutorial.


Required conditions
Basic familiarity with Angular 2 or later; installation of Node and NPM; Visual Studio Code; Bootstrap (Optional)

The command to create an Angular project is as follows.
ng new angapp

Now install Bootstrap by using the following command.
npm install bootstrap --save

Now open the styles.css file and add the Bootstrap file reference. To add a reference in the styles.css file, add this line.
@import '~bootstrap/dist/css/bootstrap.min.css';

Create a Reverse String Pipe
Now, create a custom pipe by using the following command.
ng generate pipe Reverse

Now open the Reverse.pipe.ts file and add the following code.
import { Pipe, PipeTransform } from '@angular/core';

@Pipe({ name: 'reverseString' })
export class Reverse implements PipeTransform {
  transform(value: string): string {
    if (!value) return value;
    return value.split('').reverse().join('');
  }
}


Now, create a new component by using the following command.
ng g c actionmenu

Now open searchlist.actionmenu.html file and add the following code.
<div class="container" style="margin-top:10px;margin-bottom: 24px;">
    <p>{{ 'Artificial Intelligence' | reverseString }}</p>
</div>


Now open app.component.html file and add the following code.
<div class="container" style="margin-top:10px;margin-bottom: 24px;">
  <div class="col-sm-12 btn btn-info">
    Reverse String Pipe in Angular
  </div>
</div>
<app-actionmenu></app-actionmenu>


Now run the application using npm start and check the result:

 



AngularJS Hosting Europe - HostForLIFE.eu :: How Can I Use Angular Application to Detect Event on Clicks Outside?

clock December 12, 2023 07:01 by author Peter

Overview
This post will teach us how to recognize an event in an Angular application when a user clicks outside of a component.


Required conditions
Basic familiarity with Visual Studio Code, Angular 2 or higher, Node and NPM installed, and Bootstrap

Make an Angular Project
The command to create an Angular project is as follows.

ng new angapp

Now install Bootstrap by using the following command,
npm install bootstrap --save

Now open the styles.css file and add Bootstrap file reference. To add a reference in the styles.css file add this line.
@import '~bootstrap/dist/css/bootstrap.min.css';

Now create a new component by using the following command,
ng g c actionmenu

Now open actionmenu.component.html file and add the following code.
<div class="sidebar {{show}} panel-group" clickOutside (clickOutside)="works()">
    <div class=" panel panel-default" >
        <div>
            <div class="panel-body">Panel Body</div>
            <div class="panel-footer">Panel Footer</div>
        </div>
    </div>
</div>


Now open actionmenu.component.ts file and add the following code.
import { Component, Input } from '@angular/core';

@Component({
  selector: 'app-actionmenu',
  templateUrl: './actionmenu.component.html',
  styleUrls: ['./actionmenu.component.css']
})
export class ActionmenuComponent {
  @Input() show: boolean=true;

  works() {
    this.show = !this.show;
  }
}


Now open actionmenu.component.css file and add the following code.
.sidebar {
    display: none;
}

.true {
    display: block;
}

.false {
    display: none;
}


Now open app.component.html file and add the following code.
<div class="container" style="margin-top:10px;margin-bottom: 24px;">
  <div class="col-sm-12 btn btn-info">
    How to detect clicks outside in Angular  Application
  </div>
</div>
<div class="container">
  <button type="button" class="btn btn-success" (click)="show = !show">Primary</button>
  <app-actionmenu [show]="show"></app-actionmenu>
</div>


Now open app.component.ts file and add the following code.
import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'Angular App';
  show:boolean= false;
}


Now create a new directive by using the following command, and the following code in this directive.
ng g directive clickOutside

import { Directive, ElementRef, Input, Output, HostListener, EventEmitter } from '@angular/core';

@Directive({
    selector: '[clickOutside]'
})

export class ClickOutsideDirective {

    constructor(private elementRef: ElementRef) {}

    @Output() clickOutside: EventEmitter<any> = new EventEmitter();

    @HostListener('document: click', ['$event.target']) onMouseEnter(targetElement:any) {
        const clickInside = this.elementRef.nativeElement.contains(targetElement);
        if (!clickInside) {
            this.clickOutside.emit(null);
        }
    }
}

Now open app.module.ts and following code.
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { ActionmenuComponent } from './actionmenu/actionmenu.component';
import { ClickOutsideDirective } from './click-outside.directive';
@NgModule({
  declarations: [
    AppComponent,
    ActionmenuComponent,ClickOutsideDirective
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }


Now run the application using npm start and check the result.


Click outside anyplace in the component after clicking the button. This tutorial taught us how to detect events in the Compoent Angular application when a user clicks outside of any location.



AngularJS Hosting Europe - HostForLIFE.eu :: Frontend Frameworks Decoding

clock November 29, 2023 09:06 by author Peter

In the ever-changing world of web development, selecting a front-end framework is analogous to deciding on a skyscraper's foundation. It must be tough, adaptable, and well-suited to the job at hand. Understanding the subtleties of multiple frameworks is critical for creating seamless and responsive user interfaces as developers. This essay delves into the complexities of various prominent frontend frameworks, including React.js, Angular, Vue.js, Svelte, and Ember.js, revealing their distinct capabilities and optimal use cases.

React.js
React.js, a Facebook product, is at the forefront of frontend development. Its claim to fame is its component-based architecture, which allows for the creation of modular and reusable user interfaces. The virtual DOM in React assures optimal rendering speed, making it an excellent choice for single-page applications (SPAs) and scenarios requiring real-time changes.

Case Studies

  • React's ability to swiftly update and render components makes it a standout performer for SPAs, giving users with a seamless and dynamic experience.
  • Component-Based Architecture: React.js is extremely useful for developers who want a modular and scalable development strategy. Code reuse and maintainability are aided by the ability to design self-contained components.
  • Real-Time Applications: From live conversations to collaborative editing, React's virtual DOM shines in applications requiring rapid updates and real-time interactions.

Angular
Angular is a full-fledged framework developed by Google that is meant for sturdy and feature-rich apps. Its Model-View-Controller (MVC) architecture offers a structured framework for large-scale projects. The robust capabilities in Angular's armory, including as two-way data binding and dependency injection, make it a force to be reckoned with in enterprise-level applications.

Use Cases

  • Enterprise-level Applications: Angular's comprehensive feature set and MVC architecture make it a powerhouse for building large-scale applications with complex requirements.
  • Progressive Web Apps (PWAs): With built-in service workers and a focus on performance, Angular is a go-to choice for crafting high-quality PWAs that deliver a native app-like experience.
  • Data-Intensive Applications: Projects requiring heavy data manipulation benefit from Angular's two-way data binding, simplifying the process of managing and updating data.

Vue.js
Vue.js is a frontend framework that stands out for its simplicity and versatility. Vue.js, created by Evan You, has a progressive approach, allowing developers to smoothly integrate it into projects of varied sizes. Because of its lightweight nature and adaptability, it is an ideal solution for small to medium-sized projects, as well as scenarios requiring rapid prototyping.

Use Cases
Small to Medium-sized Projects: Vue.js's lightweight nature and easy learning curve make it an excellent fit for projects where simplicity and efficiency are paramount.
Prototyping: Rapid prototyping becomes a breeze with Vue.js, as its simplicity allows developers to iterate quickly over designs and concepts.
Highly Customizable Projects: Vue.js offers a high degree of customization, making it suitable for projects that demand tailored solutions and adaptability.

Svelte

Svelte, a relative newcomer to the frontend scene, takes a different approach by shifting the heavy lifting from the browser to the build step. It compiles components into highly optimized JavaScript at build time, resulting in smaller and faster applications.

Use Cases

  • Performance-Critical Applications: Svelte's compilation approach results in highly optimized code, making it suitable for applications where performance is a top priority.
  • Developer Experience: With a syntax that closely resembles standard HTML and JavaScript, Svelte offers a refreshing developer experience, reducing boilerplate code and enhancing readability.
  • Small to Medium-sized Projects: Svelte's compilation model makes it an efficient choice for smaller projects where rapid development is crucial.


Ember.js

Ember.js, an opinionated framework, comes with conventions that guide developers through the entire application development lifecycle. It focuses on productivity and developer happiness by providing a set structure and conventions for building ambitious web applications.

Use Cases
arge-Scale Applications: Ember.js shines in projects requiring a high level of organization and structure, making it an excellent choice for large-scale applications.

  • Opinionated Development: Teams that prefer clear conventions and predefined structures benefit from Ember.js's opinionated approach, reducing decision fatigue and promoting consistency.
  • Long-term Maintenance: The conventions and structure of Ember.js contribute to long-term maintainability, making it suitable for projects with extended lifecycles.


Conclusion

In the dynamic landscape of frontend development, the choice between React.js, Angular, Vue.js, Svelte, and Ember.js is a nuanced decision influenced by the specific needs of each project. React.js excels in SPAs and real-time applications, Angular proves its mettle in enterprise-level and data-intensive projects, Vue.js provides a lightweight and flexible solution for smaller projects and rapid prototyping, Svelte offers optimized performance with a unique compilation approach, and Ember.js provides a structured, opinionated framework for large-scale applications. By carefully considering the unique features and strengths of each framework, developers can make informed decisions that align with project requirements, ensuring the successful creation of web applications that stand the test of time.



About HostForLIFE.eu

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