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firstProject

This project was generated with Angular CLI version 14.2.6.

Development server

Run ng serve for a dev server. Navigate to http://localhost:4200/. The application will automatically reload if you change any of the source files.

Code scaffolding

Run ng generate component component-name to generate a new component. You can also use ng generate directive|pipe|service|class|guard|interface|enum|module.

Build

Run ng build to build the project. The build artifacts will be stored in the dist/ directory.

Running end-to-end tests

Run ng e2e to execute the end-to-end tests via a platform of your choice. To use this command, you need to first add a package that implements end-to-end testing capabilities.

Steps to Create & Run the Project

Step -1 select a 1 folder => to install a angular cli npm install -g @angular/cli@14.2.6

  1. Output added 228 packages in 4s

    45 packages are looking for funding run npm fund for details

Step -2 Creating a Project ng new like, firstProject ex:- ng new firstProject 2. Output ng new firstProject ? Would you like to add Angular routing? Yes ? Which stylesheet format would you like to use? CSS CREATE firstProject/angular.json (2953 bytes) CREATE firstProject/package.json (1044 bytes) CREATE firstProject/README.md (1066 bytes) CREATE firstProject/tsconfig.json (863 bytes) CREATE firstProject/.editorconfig (274 bytes) CREATE firstProject/.gitignore (548 bytes) CREATE firstProject/.browserslistrc (600 bytes) CREATE firstProject/karma.conf.js (1430 bytes) CREATE firstProject/tsconfig.app.json (287 bytes) CREATE firstProject/tsconfig.spec.json (333 bytes) √ Packages installed successfully.
warning: in the working copy of 'tsconfig.json', LF will be replaced by CRLF the next time Git touches it warning: in the working copy of 'tsconfig.spec.json', LF will be replaced by CRLF the next time Git touches it
Successfully initialized git..

Step-3 Change Directory for what you create a workspace D:\workspace\LearnAngular>cd firstProject code . is used to open your workSpace in VS-Code D:\workspace\LearnAngular\firstProject>code .

Step-4 Open the terminal & Run your project help of any one of this Commandas npm start ||, (ng serve --open || ng serve -o) work in cmd

Step-5 Check the Version in CMD Angular :ng version Node :node -v Npm :npm -v 5. Output
Angular: 14.3.0 Angular CLI: 14.2.13 Node: 18.17.1 (Unsupported) Package Manager: npm 9.6.7 OS: win32 x64

Actively supported versions

ANGULAR NODE.JS TYPESCRIPT RXJS 17.0.x ^18.13.0 || ^20.9.0 >=4.9.3 <5.3.0 ^6.5.3 || ^7.4.0
16.1.x || 16.2.x ^16.14.0 || ^18.10.0 >=4.9.3 <5.2.0 ^6.5.3 || ^7.4.0
16.0.x ^16.14.0 || ^18.10.0 >=4.9.3 <5.1.0 ^6.5.3 || ^7.4.0
15.1.x || 15.2.x ^14.20.0 || ^16.13.0 || ^18.10.0 >=4.8.2 <5.0.0 ^6.5.3 || ^7.4.0
15.0.x ^14.20.0 || ^16.13.0 || ^18.10.0 ~4.8.2 ^6.5.3 || ^7.4.0

Usefull Angular Commands

Angular CLI :npm install -g @angular/cli@14.2.6 Versions Checking :ng version Create new Project :ng new firstProject To Run :ng serve -o||npm start Creating new Component :ng generate component <component-name>||ng g c <component-name> Don't generate test fil:ng g c <component-name> --skip-tests->ng g c login --skip-tests Creating new service :ng generate service <service-name> Creating new class :ng generate class <class-name>

firstProject Basic Flow

ng new firstProject open the firstProject folder and find the src folder open it

Step-1 : Observe the index.html file <body> <app-root></app-root> </body>

Step-2 : Open the main.ts/main.js file * It is the main entry point of the application. platformBrowserDynamic().bootstrapModule(AppModule); * Angular Bootstrap is a component that initiates or starts the Angular application. It basically controls the initialization process of the application. * bootstrapModule() will add the AppModule inside the browser -> Navigate the AppModule class

Step-3 : export class AppModule { } * Observe the bootstrap: [AppComponent] Array inSide @NgModel. * @NgModule. will have some properts, bootstrap property tells the compiler that this is an entry component and it should generate code to bootstrap the application with this component * The @NgModule decorator identifies AppModule as an NgModule class. @NgModule takes a metadata object that tells Angular how to compile and launch the application. * Navigate the AppModule class to AppComponent Step-4 : * What ever the bootstrap property value is there it will nagivate to that component AppComponent * observe the selector value and Step-1 tag are same . * The CSS selector that identifies this directive in a template and triggers instantiation of the directive. ->selector: app-root,this component wherever it finds the corresponding tag in template HTML. ->templateUrl: ./app.component.html,

Connect the index.html which file name is present on templateUrl that html data will display on Browser

Step-5 : While this Process we observe the One Component to another Component Communication.

    And also hiding the HTMl data in Browser ,It show only 1st loaded html file i.e Single File.

----------------------------------------------------------------

What is Angular?

Angular is a popular open-source web application framework developed by Google. It simplifies the process of building dynamic, single-page web applications (SPAs) by providing a structured framework and a set of tools.

Components:

Components are the building blocks of an Angular application. They encapsulate the application's UI and logic. Each component represents a part of the user interface and can have its own functionality.

Modules:

Modules in Angular are used to organize and structure the application. They group related components, directives, pipes, and services. A typical Angular application is comprised of multiple modules.

Services:

Services in Angular are reusable pieces of code that provide specific functionality or data across different parts of an application. They are commonly used for handling data, business logic, or communication with external services.

Directives:

Directives are markers on a DOM element that tell Angular to do something with that element. They can be structural (changing the structure of the DOM) or attribute-based (changing the appearance or behavior of an element).

Templates:

Templates in Angular are used to define the structure of the user interface. They are HTML files that include Angular-specific syntax to bind data, display dynamic content, and define the layout.

Dependency Injection:

Dependency Injection (DI) is a design pattern in Angular where the components and services rely on external dependencies being injected into them, rather than creating or managing those dependencies themselves. This promotes reusability and testability of the code.

In simple terms, Angular is a framework for building web applications using components that are organized into modules. Services provide functionality, directives manipulate the DOM, templates define the UI, and dependency injection ensures a clean and modular code structure.

Data Binding:

Data binding in Angular is a way to establish a connection between the application's data and the user interface. There are four types of data binding in Angular: One-way binding – [] Two-way binding – [()] Event binding – () Property binding – []

  1. One-Way Binding:

    • From Component to View (Interpolation): Binding data from the component to the view using curly braces {{ }}.
    • From Component to View (Property Binding): Binding data from the component to a property of an HTML element using square brackets [ ].

  2. One-Way Binding (Event Binding):

    • From View to Component: Binding events from the view to the component using parentheses ( ).

  3. Two-Way Binding:

    • Bi-Directional Binding (ngModel): Combining property binding and event binding to establish a two-way connection between the component and the view.

Directive in Angular:

A directive in Angular is a special token in the markup that tells the framework to do something to a DOM element. Directives are used to extend the behavior of HTML elements, attributes, or even create entirely new behaviors. They play a crucial role in building dynamic and interactive web applications.

Types of Directives:

  1. Components Directive:

    • Definition: Components are directives with their own templates (HTML).It encapsulates both the logic and the UI.
    • Use Case: Components are used to create reusable, self-contained parts of the user interface. They have their own structure, behavior, and styling.

  2. Structural Directives:

    • Definition: Structural directives change the structure of the DOM by adding, removing, or manipulating elements based on certain conditions.
    • Examples: ngIf for conditional rendering, ngFor for repeating elements, and ngSwitch for conditional rendering based on multiple conditions.
    • Use Case: They control the visibility and repetition of elements based on conditions. For instance, ngIf shows or hides an element, and ngFor repeats elements in a list.

  3. Attribute Directives:

    • Definition: Attribute directives change the appearance or behavior of an element by manipulating its attributes.

    • Examples: ngStyle for dynamically setting styles, ngClass for dynamically setting CSS classes, and custom attribute directives created by developers.

    • Use Case: Modifying the style, class, or behavior of an element. Examples include ngClass, ngStyle, and custom attribute directives.

    • Host Element:

      • Definition: The host element is the element on which the directive is applied. It's the element that hosts and applies the directive.
      • Use Case: Understanding the host element is crucial for attribute directives, especially when manipulating or enhancing the behavior of that specific element.

    • Host Listener:

      • Definition: Host listeners are used to respond to events on the host element. They listen for events like clicks, keypresses, etc.
      • Use Case: Suppose you have a custom directive that should perform an action when the user clicks on the element it's applied to. You'd use a host listener to listen for the click event.

    • Host Binding:

      • Definition: Host binding is used to bind a directive property to a property of the host element.
      • Use Case: If you want to dynamically change the style or content of the host element based on some condition within your directive, you'd use host binding.

  4. Custom Directives:

    • Definition: Custom directives are directives created by developers to extend or create new behavior for elements.
    • Use Case: Suppose you want a special behavior for elements that is not covered by built-in directives. You'd create a custom directive to encapsulate that behavior and reuse it across your application.

components are directives with their own templates, structural directives change the structure of the DOM, attribute directives modify appearance and behavior, and custom directives are user-defined directives created for specific requirements. They provide a powerful way to extend HTML and enhance the functionality of web applications. Understanding the host element, host listeners, and host binding is essential when working with attribute directives.

Services

In Angular, services are a fundamental part of the architecture and are used to share data, functionality, or any kind of logic across components.

  • Creating Services in Angular:
  1. Create a Service:
    • Use Angular CLI or manually create a TypeScript file for your service.
    • ng generate service serviceName/ ng g s servicename is a CLI command to create a service.
  2. Inject the Service:
    • In the component where you want to use the service, inject it in the constructor.
    • Use Angular's dependency injection system.
  3. Define Service Methods:
    • Implement the necessary methods and properties in the service.
  4. Register Service:
    • Register the service in the module by adding it to the providers array or use the providedIn property in the @Injectable decorator.
  5. Use Service:
    • Access the service methods and properties within your components.
  • Why Services in Angular:

-> Code Reusability:

  • Services promote code reusability by allowing you to centralize and share logic across components. -> Data Sharing:
  • Services are used to share data between components, especially when components are not directly related. -> For Business Logic:
  • Place business logic that is not directly related to a specific component in a service for better code organization. -> API Interaction:
  • If your application communicates with APIs, use services to encapsulate the API calls and manage the data flow. -> Cross-Component Communication:
  • When components need to communicate with each other without a direct parent-child relationship. -> State Management:
  • Services can be used to manage application state, especially in conjunction with state management libraries like NgRx.
  • Subtopics of Services in Angular:
  1. Dependency Injection in Angular:
    • Understanding how Angular's dependency injection system works.
  2. Singleton Services:
    • Explanation of how services are typically singletons in Angular, meaning there is only one instance throughout the application.
  3. HTTP Client Service:
    • How to create and use the Angular HTTP client service for making HTTP requests.
  4. Observable Services:
    • Working with observables in services for handling asynchronous operations.
  5. Angular Service Lifecycle:
    • Understanding the lifecycle hooks of Angular services.

Dependency Injection :

Dependency Injection (DI) is a fundamental concept in Angular that facilitates the development of modular and maintainable applications. In Angular, the DI system is used to provide and manage the dependencies that components, services, and other Angular constructs need.

  • Key Concepts of Dependency Injection in Angular:
  1. Injection Token:
    • An injection token is a unique identifier that Angular uses to associate a dependency with a provider. It can be a class, a string, or an OpaqueToken.
  2. Provider:
    • A provider is a configuration object that tells Angular how to create a dependency or where to find a value. Providers can be registered at various levels: component level, module level, or application level.
  3. Injector:
    • An injector is responsible for creating instances of dependencies and injecting them into components, services, or other injectables. Angular's hierarchical injector system allows for the organization and sharing of dependencies.
  • Steps to Use Dependency Injection in Angular:

  1. Define a Service or Injectable:

    • Create a service class with the @Injectable decorator. This decorator marks the class as one that can be used with the Angular DI system.
    import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root',
})
export class MyService {
  // Service logic here
}

  2. Inject the Service:

    • In the component or another service where you want to use the dependency, include it in the constructor. Angular will automatically provide the required instance.
    import { Component } from '@angular/core';
import { MyService } from './my-service.service';

@Component({
  selector: 'app-my-component',
  template: '<p>{{ myServiceData }}</p>',
})
export class MyComponent {
  constructor(private myService: MyService) {}

  get myServiceData(): string {
    return this.myService.getData();
  }
}

  3. Provide the Service:

    • Specify where the service should be provided. This is done through the providedIn property in the @Injectable decorator or by adding the service to the providers array in a module.
    // Using providedIn in the @Injectable decorator
@Injectable({
  providedIn: 'root',
})
export class MyService {
  // Service logic here
}
    // Providing the service in a module
@NgModule({
  providers: [MyService],
})
export class MyModule {}
  • Dependency Injection in Practice:
  • Singleton Pattern:
    • By default, services in Angular are singletons. There is only one instance of a service throughout the application. This helps in sharing state and maintaining consistency.
  • Hierarchical Injection:
    • Angular's DI system is hierarchical. Each component has its own injector, and dependencies are resolved based on the hierarchy. If a dependency is not found in a component's injector, Angular looks up the hierarchy until it finds a provider.
  • Lazy Loading:
    • Angular modules support lazy loading, allowing you to load parts of your application on demand. Dependencies are injected and resolved appropriately, even in lazily loaded modules.
  • Testing:
    • Dependency injection makes it easier to test components and services. You can provide mock services or dependencies during testing to isolate units of code.
  • Benefits of Dependency Injection in Angular:
  1. Modularity:
    • Components and services can be developed and tested independently, promoting modularity and reusability.
  2. Readability and Maintainability:
    • Code is more readable and maintainable when dependencies are clearly defined in the constructor. It's easier to understand the dependencies of a component/service.
  3. Testing:
    • Easier unit testing is facilitated by the ability to provide mock or test implementations of services.
  4. Flexibility:
    • Components and services can be easily replaced or extended by providing alternative implementations.

Component lifecycle hooks.

  1. constructor(): The constructor is the first method called when a component is created. It's used for basic initialization and setting up initial values.

  2. ngOnChanges(changes: SimpleChanges): This hook is called when the component detects changes to its input properties. It provides information about the changes through the SimpleChanges object.

  3. ngOnInit(): ngOnInit is called once after the component is initialized. It's commonly used for initializing data, making API calls, or any other setup logic.

  4. ngDoCheck(): This hook is called during every change detection cycle. It allows you to implement custom change detection logic and perform actions based on changes.

  5. ngAfterContentInit(): Called after content (projected content using ng-content) has been initialized. Useful for initialization that depends on content initialization.

  6. ngAfterContentChecked(): Called after every check of the component's content. Useful for actions that need to be taken after content checks.

  7. ngAfterViewInit(): Called after the component's view and its child views have been initialized. It's often used for interacting with the view, like accessing DOM elements.

  8. ngAfterViewChecked(): Called after every check of the component's view and its child views. Useful for actions that need to be taken after view checks.

  9. ngOnDestroy(): This hook is called just before the component is destroyed. It's used for cleanup activities, such as unsubscribing from observables, to prevent memory leaks.

Input and Output Properties:

  • Input Properties:

    • Input properties allow data to flow from a parent component to a child component.
    • Parent components can bind data to the child component using the @Input decorator.

  • Output Properties:

    • Output properties enable communication from a child component to a parent component.
    • Child components can emit events using the @Output decorator and the EventEmitter class.

Communication Between Components:

  1. Parent to Child:

    • Using Input Properties: Pass data from a parent to a child component by binding to the child's input properties.

  2. Child to Parent:

    • Using Output Properties: Emit events from the child component using output properties, and listen for these events in the parent component.

  3. Sibling Components:

    • Using a Shared Service: Create a shared service that acts as a mediator between sibling components. Components can communicate by sharing data through the service.

data binding in Angular allows for the seamless connection between the application's data and the user interface. Input and output properties facilitate communication between components, enabling data flow from parent to child and vice versa. Components can communicate with each other through shared services or by emitting and listening to events using input and output properties.

Creating and Organizing Modules:

Module in Angular:

  • A module in Angular is a way to organize and structure the application. It groups related components, services, directives, and pipes together.

Organizing Modules:

  • Organizing modules helps in maintaining a clean and modular codebase.
  • Feature modules are created to group components, services, and other features related to a specific functionality or domain.

Feature Modules:

Feature Module:

  • A feature module is a module that encapsulates a specific feature or functionality of an Angular application.
  • It contains related components, services, directives, and pipes necessary for that feature.

Lazy Loading:

Lazy Loading:

  • Lazy loading is a technique in Angular where modules are loaded on demand, improving the application's performance.
  • Instead of loading the entire application at once, only the necessary modules are loaded when the user navigates to a specific route.

Basic Flow:

  1. Creating Modules:

    • Use modules to organize and structure the application.
    • Feature modules group components, services, and features related to a specific functionality.

  2. Feature Modules:

    • Create feature modules to encapsulate and organize features.
    • Each feature module focuses on a specific aspect of the application.

  3. Lazy Loading:

    • Implement lazy loading to load modules only when needed.
    • Improve application performance by loading modules on demand.

Module Loading Strategy:

Module loading strategy in Angular refers to the approach used to load and initialize modules within an application. It determines when and how Angular fetches and processes the code associated with different modules.

Types of Module Loading Strategies:

  1. Eager Loading:

    • Definition: Eager loading loads all the modules and their associated code when the application starts. Everything is loaded upfront.
    • Use Case: Suitable for smaller applications where the initial loading time is acceptable.

  2. Lazy Loading:

    • Definition: Lazy loading loads modules on-demand, typically when a user navigates to a specific part of the application. This helps improve initial loading performance.
    • Use Case: Ideal for larger applications with multiple features to reduce the initial load time.

  3. Preloading:

    • Definition: Preloading loads some modules in the background after the initial application load but before the user requests them. It strikes a balance between initial loading speed and on-demand loading.
    • Use Case: Beneficial for scenarios where you want to anticipate and load modules likely to be accessed soon.

  4. Custom Preloading Strategy:

    • Definition: A custom preloading strategy allows developers to define their own rules for preloading modules. It provides more control over when and how modules are loaded.
    • Use Case: Useful when specific requirements for preloading need to be tailored based on the application's characteristics.

In summary, eager loading loads everything at the beginning, lazy loading loads modules as needed, preloading anticipates and loads some modules in the background, and a custom preloading strategy provides flexibility in defining rules for module preloading in Angular applications.

Configuring and navigating routes.

  1. Redirection route: {path:'', redirectTo:'login', pathMatch:'full'} Must be First:
  • Definition: It's a common practice to have the default redirection route as the first route.
  • Explanation: Ensures that if the path is empty, it redirects to 'login' before checking other routes.
  1. Default Route:
  • Definition: The default route is the route that gets activated when the application is loaded.
  • Explanation: The Below example, if the path is empty, it redirects to the '/home' route as the default route.
  1. Complex Route / Nested Route:
  • Definition: Complex or nested routes involve creating a hierarchy of routes.
  • Explanation:The Below example, the '/dashboard' route has child routes '/dashboard/overview' and '/dashboard/details'.
  1. Params, Query, and Fragment:
  • Definition:
    • Params: Route parameters are used to pass data in the URL.
    • Query: Query parameters are used to pass data as key-value pairs in the URL.
    • Fragment: Fragments are used for scrolling to a specific section on a page.
  1. Wildcard Route:
  • Definition: The wildcard route (**) is a catch-all route that handles undefined routes.
  • Explanation: The wildcard route catches any undefined route and directs to the PageNotFoundComponent. It must in last of all paths
  1. RouterLink and RouterLinkActive :
  • Definitions:
    • RouterLink: RouterLink is used in the template for navigation.
    • RouterLinkActive: RouterLinkActive is used to add a CSS class when a link is active.
  1. [routerLinkActiveOptions]={exact:true}:
  • Definition: It's an option for RouterLinkActive to control the active class behavior.
  • Explanation: The 'active' class will only be applied if the route is exactly matched.
  1. this.router.navigate(['/home']); Navigation:
  • Definition: Programmatic navigation using the Router service. this.router.navigate(['/home']); // In your component or service
  • Explanation: Navigates to the '/home' route programmatically.

Understanding these concepts is crucial for effective navigation and route handling in Angular applications.

Forms In Angular

Forms are fundamental elements in web development, serving as a crucial bridge between users and applications. They enable the collection of user input, supporting various functionalities such as user registration, login, data filtering, feedback, and more. Forms play a key role in facilitating transactions, customization of user experiences, and compliance with legal requirements. Their versatility extends to powering interactive web applications, enhancing user engagement, and contributing to the overall functionality and usability of websites and applications. In essence, forms are the interactive backbone that empowers users to actively participate and communicate with digital platforms.

Types of Forms

1.Template-driven forms 2.Reactive Forms

Template-driven forms are one of the two types of forms in Angular, the other being Reactive forms. Here's an explanation and expansion of the points you've mentioned:

  • Template-Driven Forms in Angular:

  1. Introduction:

    • Template-driven forms are a way of creating forms in Angular by using template-driven syntax in the HTML file.

  2. Features:

    • Simple Basic Form:

      • Template-driven forms are easier to set up and are a good starting point for simple forms.

    • Easy to Start:

      • Ideal for beginners and quick development.

    • Based on Template (HTML):

      • Form structure and logic are defined directly in the HTML template.

  3. Modules and Configuration:

    • In the app.module.ts file, ensure that the FormsModule is imported from @angular/forms and added to the imports array.
    import { FormsModule } from '@angular/forms';

@NgModule({
  imports: [FormsModule],
  // other configurations
})

  4. Form Submission:

    • Use the ngSubmit directive on the <form> element to handle form submissions.
    <form (ngSubmit)="onSubmit()">
  <!-- Form controls go here -->
  <button type="submit" [disabled]="!myForm.valid">Submit</button>
</form>

  5. ngModel:

    • Use ngModel to bind form controls to properties in the component. It helps in two-way data binding.
    <input type="text" [(ngModel)]="formData.username" name="username" required>

  6. Form Validation:

    • Angular provides CSS classes to style form elements based on their validation status.

      • .ng-valid, .ng-invalid: Indicates whether the form is valid or not.
      • .ng-pristine, .ng-dirty: Indicates whether the form has been touched or modified.
      • .ng-touched, .ng-untouched: Indicates whether the form has been touched or not.
    <input type="text" [(ngModel)]="formData.username" name="username" required>
<div ngIf="myForm.controls['username'].invalid && (myForm.controls['username'].dirty || myForm.controls['username'].touched)">
  Username is required.
</div>

  7. ngModelGroup:

    • Use ngModelGroup to group form controls within a form.
    <div ngModelGroup="address">
  <input type="text" [(ngModel)]="formData.address.street" name="street" required>
  <input type="text" [(ngModel)]="formData.address.city" name="city" required>
</div>

  8. NgForm Properties:

    • Angular provides several properties that can be accessed on the NgForm object.

      • controls: All form controls in the form.
      • dirty: Indicates if any form control has been changed.
      • invalid: Indicates if any form control has validation errors.
      • valid: Indicates if all form controls are valid.
      • touched: Indicates if any form control has been touched.
    <form #myForm="ngForm">
  <!-- Form controls go here -->
</form>

These are some key points related to template-driven forms in Angular. They are suitable for simpler forms where a quick setup is required. For more complex forms and dynamic behavior, Reactive forms are often preferred.

2.Reactive Forms

HTTP and APIs:

When making HTTP requests with Angular's HttpClient for REST API integration, you often encounter the need to convert objects to strings (JSON.stringify()) and strings back to objects (JSON.parse()). Additionally, array methods like slice() and push() might be handy. Below is a brief explanation of these concepts in the context of REST API integration:

    1. HttpClient in Angular:

HttpClient in Angular is a module that provides a simplified way to make HTTP requests from an Angular application. It allows you to communicate with a server, fetch data, and send data to the server. It's a key tool for integrating your Angular application with external APIs or backend services.

    1. REST API Integration:

REST API integration involves connecting your application to a server or web service that follows the principles of Representational State Transfer (REST). RESTful APIs provide a standardized way for different systems to communicate over the web. Integration includes making HTTP requests (such as GET, POST, PUT, DELETE) to interact with the server, retrieve data, and perform actions. It forms the backbone of communication between front-end applications, like those built with Angular, and backend servers.

  1. Import HttpClientModule: Make sure to import the HttpClientModule in your Angular application. You typically do this in the AppModule or the module where you want to use HTTP.

    import { HttpClientModule } from '@angular/common/http';

@NgModule({
  imports: [HttpClientModule],
  // other configurations
})
export class AppModule { }

  2. Inject HttpClient: Inject the HttpClient service into your component or service where you want to make HTTP requests. You can do this by including it in the constructor.

    import { HttpClient } from '@angular/common/http';

constructor(private http: HttpClient) { }

  3. Making GET Request: The GET method is used to retrieve data from a specified resource. It is a read-only operation and doesn't modify the resource on the server. GET requests are typically used for fetching information like web pages, images, or any other data.

    this.http.get('https://api.example.com/data')
  .subscribe(data => {
    console.log('Response:', data);
  }, error => {
    console.error('Error:', error);
  });

  4. Making POST Request: The POST method is used to submit data to be processed to a specified resource. It is often used for creating new resources on the server. The data to be sent is included in the body of the request

    const postData = { key: 'value' };

this.http.post('https://api.example.com/post-endpoint', postData)
  .subscribe(response => {
    console.log('Response:', response);
  }, error => {
    console.error('Error:', error);
  });

  5. Making PUT Request: The PUT method is used to update a resource or create it if it doesn't exist. It replaces the entire resource with the new data provided in the request. If the resource doesn't exist, it creates a new one.

 httpClient.put('https://api.example.com/posts/1', { updatedData: 'new value' })
  .subscribe(response => {
    console.log('PUT Response:', response);
  }, error => {
    console.error('PUT Error:', error);
  });
    1. Making DELETE Request: The DELETE method is used to request the removal of a resource identified by a specific URI. It's used to delete a resource on the server.
httpClient.delete('https://api.example.com/posts/1')
  .subscribe(response => {
    console.log('DELETE Response:', response);
  }, error => {
    console.error('DELETE Error:', error);
  });
  • JSON.stringify() and JSON.parse(): When dealing with data in JavaScript, especially when making HTTP requests, it's common to convert JavaScript objects to JSON strings using JSON.stringify() before sending them in the request payload. On the receiving end, you use JSON.parse() to convert the JSON string back to a JavaScript object.

Example:

const dataObject = { key: 'value', number: 42 };
const jsonString = JSON.stringify(dataObject);// jsonString is '{"key":"value","number":42}'

const parsedObject = JSON.parse(jsonString);// parsedObject is { key: 'value', number: 42 }
  • slice(): The slice() method in JavaScript is often used with arrays to extract a portion of the array without modifying the original array. It's useful for creating a shallow copy or obtaining a subset of the array.

Example:

const originalArray = [1, 2, 3, 4, 5];
const slicedArray = originalArray.slice(1, 3);// slicedArray is [2, 3] // originalArray is still [1, 2, 3, 4, 5]
  • push(): The push() method adds one or more elements to the end of an array and returns the new length of the array.

Example:

const numbers = [1, 2, 3];
numbers.push(4, 5);// numbers is now [1, 2, 3, 4, 5]
  1. Handling Response with Observables: Angular uses Observables to handle asynchronous operations, including HTTP requests. You subscribe to the Observable to receive the response or handle errors.
    1. Headers and Parameters: You can add headers and parameters to your HTTP requests. For example:
    const headers = new HttpHeaders({
  'Content-Type': 'application/json',
  'Authorization': 'Bearer YOUR_ACCESS_TOKEN'
});

const params = new HttpParams()
  .set('param1', 'value1')
  .set('param2', 'value2');

this.http.get('https://api.example.com/data', { headers, params })
  .subscribe(data => {
    console.log('Response:', data);
  }, error => {
    console.error('Error:', error);
  });
    1. Error Handling: Always include error handling to manage situations where the HTTP request fails. This helps in providing a better user experience and debugging.

HttpClient helps your Angular app talk to servers, and REST API integration is the process of making sure your app and the server can understand and work with each other through standardized web communication.The use of Observables allows for handling asynchronous operations effectively. AngularDoc.txt Displaying AngularDoc.txt.

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