Learn Angular

This repository contains a list of resources to learn Angular.

Table of Contents

• Introduction
• Roadmap
• Configuration
• Components
• Data Binding
  • One Way Binding
  • Two Way Binding
• Directives
  • Structural Directives
  • Attribute Directives
  • Custom Directives
  • Other Directives
• Pipes
  • Date Pipe
  • Uppercase Pipe
  • Lowercase Pipe
  • Currency Pipe
  • Percent Pipe
  • Slice Pipe
  • Decimal/number Pipe
  • JSON Pipe
  • Async Pipe
• Decorators
  • Input
  • Output
  • HostListener
  • ContentChild & ContentChildren
  • ViewChild & ViewChildren
• Life Cycle Hooks
  • OnChanges
  • OnInit
  • DoCheck
  • AfterViewInit
  • AfterViewChecked
  • AfterContentInit
  • AfterContentChecked
  • OnDestroy
• Forms
• Signals
• Angular Signals
• Destroy Ref
• Http
• Module
• Router
• Route Parameter
• Observables
• Unsubscribe
• Renderer2
• Standalone Components
• JIT
• AOT
• Deferrable Views
• Meta Tags
  • Title Service
    • Dynamic Title
  • Meta Service
• CLI Commands
• Version compatibility
• Imports
• TypeScript
• RxJS
• Learn From GitHub Repositories
• Learn From Websites
• Learn From Books
• Learn From YouTube Channels
• Learn More From Blogs Sites
• List of Online Editors/Compiler for Angular
• List of Twitter Users to Follow
• List of LinkedIn Users to Follow

Introduction

Angular is a platform and framework for building single-page client applications using HTML and TypeScript. It is maintained by Google and a community of developers. Angular provides a set of tools and libraries for building web applications, including data binding, routing, forms, HTTP client, and more. Angular is based on the Model-View-Controller (MVC) architecture and uses TypeScript as the primary language for building applications.

Features of Angular

• Component-Based Architecture - Angular is based on a component-based architecture, where components are the main building blocks of an application. Components are reusable, self-contained units of code that define the UI and behavior of a part of the application.

• Two-Way Data Binding - Angular provides two-way data binding, which allows for automatic synchronization of data between the model and the view. This means that changes to the model are reflected in the view, and changes to the view are reflected in the model.

• Dependency Injection - Angular uses dependency injection to provide components with the services they need. This allows for better modularity, testability, and reusability of code.

• Routing - Angular provides a powerful routing system that allows for navigation between different views of an application. Routing is based on the URL of the application and allows for deep linking, lazy loading, and route guards.

• Forms - Angular provides a rich set of tools for working with forms, including template-driven forms and reactive forms. Forms in Angular are based on the model-driven approach, where the form controls are bound to properties in the component's class.

• HTTP Client - Angular provides an HTTP client module that allows for making HTTP requests to a server. The HTTP client module provides a simple API for working with RESTful APIs and handling responses.

• Observables - Angular uses observables to handle asynchronous operations, such as HTTP requests and event handling. Observables are a powerful way to work with asynchronous data streams and provide a consistent way to handle events in an application.

• TypeScript - Angular is built using TypeScript, a superset of JavaScript that adds static typing and other features to the language. TypeScript provides better tooling, error checking, and code completion, which makes it easier to build and maintain large applications.

• Performance - Angular is designed for performance and scalability. It uses a virtual DOM to optimize rendering performance, and provides tools for lazy loading, tree shaking, and ahead-of-time compilation to reduce the size of the application and improve performance.

• Mobile Support - Angular provides tools for building mobile applications, including responsive design, touch gestures, and mobile-specific features. Angular applications can be built as Progressive Web Apps (PWAs) and deployed to mobile devices using Cordova or Capacitor.

• SEO Friendly - Angular provides tools for building SEO-friendly applications, including server-side rendering, pre-rendering, and meta tags. Angular applications can be optimized for search engines to improve visibility and ranking in search results.

• Community Support - Angular has a large and active community of developers, who contribute to the framework, provide support, and share knowledge through blogs, forums, and social media. The Angular community is known for its helpfulness, inclusivity, and diversity.

Difference between AngularJS vs Angular

Roadmap

https://roadmap.sh/angular

Configuration

Prerequisites

• Node.js

Installation

Install the Angular CLI globally:

npm install -g @angular/cli

Check version

ng version

Create workspace:

ng new [PROJECT NAME]

Run the application:

cd [PROJECT NAME]
ng serve

Components

Component is the main building block of an Angular Application. It is a TypeScript class that interacts with the HTML template and provides the data and logic to the view.

Three main building blocks

• Template
• Class
• Metadata

Template - Defines the layout and content of the View.

Class - Class provides the data & logic to the View.

MetaData - Metadata Provides additional information about the component to the Angular.

Component metadata properties

• Selector
• Providers
• Styles
• StyleUrls
• Template
• TemplateUrl

Selector - Defines the element name or CSS selector that identifies the component in the HTML template.

Providers - Defines the providers of the component's dependencies.

styles - Defines the inline styles for the component.

styleUrls - Defines an array of URLs of the stylesheets for the component.

template - Defines the HTML template for the component.

templateUrl - Defines the URL of the HTML template for the component.

Component Creation

Using Angular CLI

ng generate component [component-name]

Manual Creation

Step 1 - Create a new folder for the component inside the src/app folder.

src/app/[component-name]

Step 2 - Create a new TypeScript file for the component inside the new folder.

src/app/[component-name]/[component-name].component.ts

Step 3 - Create a new HTML file for the component inside the new folder.

src/app/[component-name]/[component-name].component.html

Step 4 - Create a new CSS file for the component inside the new folder.

src/app/[component-name]/[component-name].component.css

Step 5 - Import the Component class from the @angular/core module.

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

Step 6 - Decorate the class with the @Component decorator.

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

Step 7 - Define the selector, template, and styles for the component.

selector - The selector for the component.
templateUrl - The URL of the HTML template for the component.
styleUrls - An array of URLs of the stylesheets for the component.

Step 8 - Export the class.

export class [ComponentName]Component {
}

Step 9 - Import the component class in the app.module.ts file.

import { [ComponentName]Component } from './[component-name]/[component-name].component';

Step 10 - Add the component to the declarations array in the @NgModule decorator.

declarations: [
  AppComponent,
  [ComponentName]Component
]

Step 11 - Use the component selector in the HTML template of the app.component.ts file.

<app-[component-name]></app-[component-name]>

Step 12 - Run the application using the ng serve command.

ng serve

Example

Creating the component files -

//test-component.component.ts
import { Component } from '@angular/core';

@Component({
  selector: 'test-component',
  templateUrl: './component.component.html',
  styleUrls: ['./component.component.css']
})

export class TestComponent {

}

<!--component.component.html-->
<h1>Test Component</h1>

/*component.component.css*/
h1 {
  color: red;
}

Importing the component in the app.module.ts file -

//app.module.ts
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
 
import { AppComponent } from './app.component';
import { TestComponent } from './app.component';

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

Creating the inline Template & StyleUrls -

import { Component } from '@angular/core';
 
@Component({
  selector: 'app-root',
  template: '<h1> {{title}} works </h1>',
  styles: ['h1 { font-weight: bold; }']
})
export class AppComponent {
  title = 'app';
}

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Data binding

One way binding

a. From Component to View - This allows for passing data from the component's class to the HTML template.

Interpolation - This allows for embedding expressions in the HTML template. It is denoted by double curly braces ({{}}).

Example :

<h1>{{ firstText }} {{ lastText }}</h1>

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  firstText = 'Interpolation';
  lastText = 'Example';
}

Stackblitz Example

Property binding - This allows for binding a property of an HTML element to a property in the component's class. It is denoted by square brackets ([]).

Example :

<h1 [innerText]="title"></h1>

<button [disabled]="isDisabled">I am disabled</button>

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  title = 'Angular Property Binding Example';

  isDisabled = true;
}

Stackblitz Example

class binding - This allows for binding a class of an HTML element to a property in the component's class. It is denoted by square brackets ([]).

Example :

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  isActive = false;

  toggleActive() {
    this.isActive = !this.isActive;
  }
}

<div [class.active]="isActive">This div is active.</div>
<button (click)="toggleActive()">Toggle Active</button>

.active {
  background-color: yellow;
}

Stackblitz Example

style binding - This allows for binding a style of an HTML element to a property in the component's class. It is denoted by square brackets ([]).

Example :

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  backgroundColor = 'red';
  textColor = 'white';
}

<div [style.background-color]="backgroundColor">
  <h1 [style.color]="textColor">Hello, world!</h1>
</div>

Stackblitz Example

attribute binding - This allows for binding an attribute of an HTML element to a property in the component's class. It is denoted by square brackets ([]).

Example :

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  imageUrl = 'https://example.com/image.jpg';
  imageAlt = 'Example image';
  isButtonDisabled = false;
}

<img [attr.src]="imageUrl" [attr.alt]="imageAlt">
<button [attr.disabled]="isButtonDisabled">Click me</button>

Stackblitz Example

b. From View to Component - This allows for passing data from the HTML template to the component's class.

Event binding - This allows for binding an event of an HTML element to a method in the component's class. It is denoted by parentheses (()).

Example :

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  onClick() {
    console.log('Button was clicked');
  }
}

<h1>Event Binding Example</h1>
<button (click)="onClick()">Click me</button>

Stackblitz Example

Remeber💡

The (click) calls the specified function when a user clicks on the given element (in your example, when a user clicks on a row).

The (change) event binds to HTML's onChange event. This event is fired for `<input>`, `<select>`, and `<textarea>` elements when a change to the element's value is committed by the user.

The (change) event can also be specifically implemented by other Angular components. It is generally implemented on components where the contents of the component are changed by the user.

☝️Source of Explaination

Two ways binding

This allows for binding a property of an HTML element to a property in the component's class and vice-versa. This is done by using a combination of property binding and event binding. It is denoted by [(ngModel)].

ngModel -

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  name: string = '';
}

<input [(ngModel)]="name" placeholder="Enter your name">
<p>Your name is: {{name}}</p>

Stackblitz Example

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Directives

Directives add behaviour to an existing DOM element or an existing component instance.

Structural Directives

ngFor - The ngFor directive is used to iterate over a list of items and create a template for each item. It is commonly used to display a list of items in the UI.

Example :

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

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

export class AppComponent {
  items = ['Item 1', 'Item 2', 'Item 3'];
}

<h1>ngFor Example</h1>
<ul>
  <li *ngFor="let item of items">{{ item }}</li>
</ul>

Stackblitz Example

ngSwitch - The ngSwitch directive is used to conditionally display elements based on the value of a given expression. It is similar to a switch statement in JavaScript.

Example :

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  value = 1;
}

<h1>ngSwitch Example</h1>
<div [ngSwitch]="value">
  <div *ngSwitchCase="1">Case 1</div>
  <div *ngSwitchCase="2">Case 2</div>
  <div *ngSwitchCase="3">Case 3</div>
  <div *ngSwitchDefault>Default case</div>
</div>

Stackblitz Example

ngIf - The ngIf directive is used to conditionally display elements based on the value of a given expression. It is commonly used to show or hide elements in the UI based on certain conditions.

Example :

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  showElement = true;
}

<h1>ngIf Example</h1>
<div *ngIf="showElement">
  This element will only be displayed if showElement is true.
</div>

Stackblitz Example

Attribute Directives

ngModel - The ngModel directive is used to create two-way data binding between an input element and a property in the component's class. It is commonly used to bind form controls to properties in the component.

Example :

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  name: string;
}

<h1>ngModel Example</h1>
<form>
  <label for="name">Name:</label>
  <input type="text" id="name" [(ngModel)]="name" name="name" />
</form>

Stackblitz Example

ngClass - The ngClass directive is used to conditionally apply CSS classes to an element based on the value of a given expression. It is commonly used to apply styles to elements based on certain conditions.

Example :

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  isHighlighted = true;
}

<h1>ngClass Example</h1>
<div [ngClass]="{ highlighted: isHighlighted }">
  This element will have the 'highlighted' class if isHighlighted is true.
</div>

.highlighted {
  background-color: yellow;
}

Stackblitz Example

ngStyle - The ngStyle directive is used to conditionally apply inline styles to an element based on the value of a given expression. It is commonly used to apply dynamic styles to elements based on certain conditions.

Example :

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  color = 'red';
}

<h1>ngStyle Example</h1>
<div [ngStyle]="{ color: color }">
  This element will have the color style set to the value of the color property.
</div>

Stackblitz Example

Custom Directives

Custom directives are used to add custom behavior to elements in the DOM. They are created using the @Directive decorator and can be applied to elements as attributes, classes, or elements.

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

@Directive({
  selector: '[appCustomDirective]',
})
export class CustomDirectiveDirective {
  constructor(private el: ElementRef) {}

  @HostListener('mouseenter') onMouseEnter() {
    this.highlight('yellow');
  }

  @HostListener('mouseleave') onMouseLeave() {
    this.highlight(null);
  }

  private highlight(color: string) {
    this.el.nativeElement.style.backgroundColor = color;
  }
}

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';

import { AppComponent } from './app.component';
import { CustomDirectiveDirective } from './custom-directive.directive';

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

<h1>Custom Directive Element</h1>
<div appCustomDirective>
  This element will have a yellow background when the mouse is over it.
</div>

Stackblitz Example

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Other directives

ngContainer, ngTemplate, ngContent, ngTemplateOutlet are some of the other directives in Angular.

ngContainer - The ngContainer directive is a simple container that doesn't generate any markup in the DOM. It's mainly used as a placeholder to group and structure content within Angular templates.

Example :

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

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

export class AppComponent {
  condition = true;
}

<h1>ngContainer Example</h1>
<div *ngIf="condition">
  <ng-container>
    <p>Content to be conditionally rendered</p>
    <p>More content...</p>
  </ng-container>
</div>

Stackblitz Example

ngTemplate - The ngTemplate directive is used to define a reusable template block that can be used later within the same component or shared across components using the ngTemplateOutlet directive.

Example :

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

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

export class AppComponent {
  selectedTemplate: any;
}

<h1>ngTemplate Example</h1>
<ng-template #myTemplate>
  <p>This is a template</p>
  <p>It can be reused in multiple places</p>
</ng-template>

<div>
  <ng-container *ngTemplateOutlet="selectedTemplate"></ng-container>
</div>

<button (click)="selectedTemplate = myTemplate">Load Template</button>

Stackblitz Example

ngContent - The ngContent directive is used for content projection or transclusion. It allows you to create reusable components with customizable content.

Example :

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

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

export class ChildComponent {}

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

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

export class ParentComponent {}

<!-- Parent Component -->
<app-child>
  <p>Content projected into the child component</p>
</app-child>

<!-- Child Component Template -->
<div>
  <ng-content></ng-content>
</div>

Stackblitz Example

ngTemplateOutlet - The ngTemplateOutlet directive is used to render a template defined using ngTemplate. It allows you to dynamically render a template within a component's template.

Example :

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

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

export class AppComponent {
  selectedTemplate: any;
}

<h1>ngTemplateOutlet Example</h1>
<ng-container *ngTemplateOutlet="selectedTemplate"></ng-container>

<ng-template #template1>
  Template 1 content
</ng-template>

<ng-template #template2>
  Template 2 content
</ng-template>

<button (click)="selectedTemplate = template1">Load Template 1</button>
<button (click)="selectedTemplate = template2">Load Template 2</button>

Stackblitz Example

Pipes

A pipe takes in data as input and transforms it to a desired output.

Syntax

Expression | pipeOperator[:pipeArguments]

# Expression: is the expression, which you want to transform
# | : is the Pipe Character
# pipeOperator : name of the Pipe
# pipeArguments: arguments to the Pipe

Date Pipe

The date pipe is used to format a date value according to the locale rules specified in the application.

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  date = new Date();

  constructor(private datePipe: DatePipe) {}

  formatDate() {
    return this.datePipe.transform(this.date, 'shortDate');
  }
}

<h1>Date Pipe Example</h1>
<p>{{ date | date: 'shortDate' }}</p>

import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';

import { AppComponent } from './app.component';
import { DatePipe } from '@angular/common';

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

Uppercase Pipe

The uppercase pipe is used to transform a string to uppercase.

<h1>Upper Case Pipe Example</h1>
<p>{{ name | uppercase }}</p>

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  name = 'Manthan Ank';
}

Lowercase Pipe

The lowercase pipe is used to transform a string to lowercase.

<p>{{ name | lowercase }}</p>

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  name = 'Manthan Ank';
}

Currency Pipe

The currency pipe is used to format a number as currency using the locale rules specified in the application.

<h1>Currency Pipe Example</h1>
<p>{{ price | currency }}</p>

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  price = 100;

  constructor(private currencyPipe: CurrencyPipe) { }

  formatCurrency() {
    return this.currencyPipe.transform(this.price, 'USD', true);
  }
}

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';

import { AppComponent } from './app.component';
import { CurrencyPipe } from '@angular/common';

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

Percent Pipe

The percent pipe is used to format a number as a percentage.

<h1>Percent Pipe Example</h1>
<p>{{ percentage | percent }}</p>

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  percentage = 0.5;

  constructor(private percentPipe: PercentPipe) {}

  formatPercentage() {
    return this.percentPipe.transform(this.percentage, '2');
  }
}

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';

import { AppComponent } from './app.component';
import { HelloComponent } from './hello.component';
import { PercentPipe } from '@angular/common';

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

Slice Pipe

The slice pipe is used to create a new array or string containing a subset of the elements of the input array or string.

<p>{{ ['apple', 'banana', 'orange', 'mango'] | slice:1:3 }}</p>

Decimal/number Pipe

The number pipe is used to format a number as text. It can be used to format a number as a percentage, currency, or decimal number.

<p>{{ 123456.78 | number:'3.2-3' }}</p>

JSON Pipe

The json pipe is used to transform a JavaScript object into a JSON string.

<p>{{data | json}}</p>

Async Pipe

The async pipe is used to subscribe to an Observable or Promise and return the latest value it has emitted.

<p>{{data$ | async}}</p>

// DataService.service.ts
import { Injectable } from '@angular/core';
import { Observable, of } from 'rxjs';

@Injectable()
export class DataService {
  private data$: Observable<string>;

  constructor() {
    // Simulating an asynchronous data source
    this.data$ = of('Hello, async pipe!').pipe(
      // Simulating delay
      delay(2000)
    );
  }

  getData(): Observable<string> {
    return this.data$;
  }
}

// ExampleComponent.component.ts
import { Component } from '@angular/core';
import { Observable } from 'rxjs';
import { DataService } from './data.service';

@Component({
  selector: 'app-example',
  template: '<div>{{ data$ | async }}</div>',
})
export class ExampleComponent {
  data$: Observable<string>;

  constructor(private dataService: DataService) {
    this.data$ = this.dataService.getData();
  }
}

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Decorators

Decorators are design patterns used to isolate the modification or decoration of a class without modifying the source code.

Input

The @Input decorator is used to pass data from a parent component to a child component.

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

@Component({
  selector: 'app-child',
  templateUrl: './child.component.html',
  styleUrls: ['./child.component.css']
})
export class ChildComponent implements OnInit {
  @Input() message: string;
  constructor() { }

  ngOnInit() {
    
  }

}

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

@Component({
  selector: 'app-parent',
  templateUrl: './parent.component.html',
  styleUrls: ['./parent.component.css'],
})
export class ParentComponent implements OnInit {
  parentMessage = 'Hello from the parent component!';
  constructor() {}

  ngOnInit() {}
}

<p>{{ message }}</p>

<app-child [message]="parentMessage"></app-child>

<h1>@Input Example</h1>
<app-parent></app-parent>

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';

import { AppComponent } from './app.component';
import { RouterModule } from '@angular/router';
import { ChildComponent } from './child/child.component';
import { ParentComponent } from './parent/parent.component';

@NgModule({
  imports: [BrowserModule, FormsModule, RouterModule],
  declarations: [AppComponent, ChildComponent, ParentComponent],
  bootstrap: [AppComponent],
})
export class AppModule {}

Output

The @Output decorator is used to pass data from a child component to a parent component.

import { Component, EventEmitter, OnInit, Output } from '@angular/core';

@Component({
  selector: 'app-child',
  templateUrl: './child.component.html',
  styleUrls: ['./child.component.css'],
})
export class ChildComponent implements OnInit {
  @Output() messageEvent = new EventEmitter<string>();

  constructor() {}

  ngOnInit() {}

  sendMessage() {
    this.messageEvent.emit('Hello from the child component!');
  }
}

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

@Component({
  selector: 'app-parent',
  templateUrl: './parent.component.html',
  styleUrls: ['./parent.component.css'],
})
export class ParentComponent implements OnInit {
  constructor() {}

  ngOnInit() {}

  handleMessage(message: string) {
    console.log(message);
  }
}

<button (click)="sendMessage()">Send message</button>

<app-child (messageEvent)="handleMessage($event)"></app-child>

<h1>@Output Decorator Example</h1>
<app-parent></app-parent>

HostListener

The @HostListener decorator is used to listen for events on the host element of a directive or component.

<h1>@HostListener Decorator Example</h1>
<p>Click the host element to trigger the 'click' event.</p>

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  @HostListener('click')
  onClick() {
    console.log('The host element was clicked!');
  }
}

contentChild & contentChildren

The @ContentChild and @ContentChildren decorators are used to query for content children in the component's view.

import {
  Component,
  ContentChild,
  ContentChildren,
  ElementRef,
  OnInit,
  QueryList,
} from '@angular/core';

@Component({
  selector: 'app-parent',
  templateUrl: './parent.component.html',
  styleUrls: ['./parent.component.css'],
})
export class ParentComponent implements OnInit {
  @ContentChild('childButton1', { static: true }) childButton1: ElementRef;
  @ContentChildren('childButton2') childButtons2: QueryList<ElementRef>;

  ngAfterContentInit() {
    console.log(this.childButton1.nativeElement.textContent);
    this.childButtons2.forEach((button) => {
      console.log(button.nativeElement.textContent);
    });
  }

  constructor() {}

  ngOnInit() {}
}

<ng-content></ng-content>

<h1>@ContentChild Decorator Example</h1>
<app-parent></app-parent>

viewChild & viewChildren

The @ViewChild and @ViewChildren decorators are used to query for view children in the component's view.

import { Component, ElementRef, QueryList, ViewChild, ViewChildren } from '@angular/core';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  @ViewChild('childButton1', { static: true }) childButton1: ElementRef;
  @ViewChildren('childButton2') childButtons2: QueryList<ElementRef>;

  ngAfterViewInit() {
    console.log(this.childButton1.nativeElement.textContent);
    this.childButtons2.forEach(button => {
      console.log(button.nativeElement.textContent);
    });
  }
}

<h1>@viewChild & @viewChildren Example</h1>
<button #childButton1>Button 1</button>
<button #childButton2>Button 2</button>

Back to top⤴️

Life Cycle Hooks

OnChanges

It is called when the data-bound properties of a directive/component are changed. It is called before ngOnInit and whenever one or more data-bound input properties change.

<form>
  <input [(ngModel)]="message" name="message" />
  <button type="submit" (click)="onSubmit()">Submit</button>
</form>
<p>{{ message }}</p>

import {
  Component,
  Input,
  OnChanges,
  OnInit,
  SimpleChanges,
} from '@angular/core';

@Component({
  selector: 'app-test',
  templateUrl: './test.component.html',
  styleUrls: ['./test.component.css'],
})
export class TestComponent implements OnChanges {
  @Input() message: string;
  prevMessage: string;

  ngOnChanges(changes: SimpleChanges) {
    if (changes.message) {
      console.log(
        `message changed from ${changes.message.previousValue} to ${changes.message.currentValue}`
      );
    }
  }

  onSubmit() {
    this.prevMessage = this.message;
  }
}

<app-test  [message]="'Hello World'"></app-test>

Stackblitz Link

OnInit

It is called after Angular has initialized all data-bound properties of a directive/component. It is called only once after the first ngOnChanges.

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

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

  ngOnInit() {
    console.log('logged from ngOnInit');
  }
}

Stackblits Link

DoCheck

It is called during every change detection run, and it is used to detect and act upon changes that Angular doesn't catch on its own.

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent implements DoCheck {
  ngDoCheck() {
    console.log('ngDoCheck Called');
  }
}

Stackblitz Link

AfterViewInit

It is called after Angular has fully initialized a component's view. It is the perfect place to put any initialization logic that depends on the view.

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent implements AfterViewInit{
  
  ngAfterViewInit(){
    console.log("after view init")
  }
  clickMe(){
    console.log("link clicked")
  }
}

<a (click)="clickMe()">Click me</a>

Stackblitz Link

AfterViewChecked

It is called after Angular has checked the component's view and child views. It is called after ngAfterViewInit and every subsequent ngAfterContentChecked.

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent implements AfterViewChecked {
  ngAfterViewChecked(){
    console.log("after view checked")
  }
  clickMe(){
    console.log("link clicked")
  }
}

<a (click)="clickMe()">Click me</a>

Stackblitz Link

AfterContentInit

It is called after Angular has fully initialized the content of a directive. It is the perfect place to put any initialization logic that depends on the content.

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent implements AfterContentInit {
  ngAfterContentInit() {
    console.log('after content init');
  }
  clickMe() {
    console.log('clicked');
  }
}

<a (click)="clickMe()">Click me</a>

Stackblitz Link

AfterContentChecked

It is called after the default change detector has completed checking all content of a directive. It is called after ngAfterContentInit and every subsequent ngAfterContentChecked.

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

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent implements AfterContentInit {
  ngAfterContentChecked() {
    console.log('after content init');
  }
  clickMe() {
    console.log('clicked');
  }
}

<a (click)="clickMe()">Click me</a>

Stackblitz Link

OnDestroy

It is called just before Angular destroys the directive/component. It is used to cleanup any resources or subscriptions that the directive/component has created.

import { Component, OnDestroy, OnInit } from '@angular/core';
import { Subscription } from 'rxjs';
import { of } from 'rxjs';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent implements OnInit, OnDestroy {
  private subscription: Subscription;

  ngOnInit() {
    const someObservable = of(1, 2, 3);
    this.subscription = someObservable.subscribe((data) => {
      console.log(data);
    });
  }

  ngOnDestroy() {
    this.subscription.unsubscribe();
  }
}

Stackblitz Link

Back to top⤴️

Forms

Template Driven Form

<form (ngSubmit)="onSubmit()" #form="ngForm">
    <input [(ngModel)]="name" name="name" required>
    <button type="submit">Submit</button>
</form>

Example

<!-- form template -->
<form (ngSubmit)="onSubmit(form)" #form="ngForm">
  <label>
    Name:
    <input type="text" [(ngModel)]="name" name="name" required>
  </label>
  <br>
  <label>
    Email:
    <input type="email" [(ngModel)]="email" name="email" required>
  </label>
  <br>
  <button type="submit" [disabled]="!form.valid">Submit</button>
</form>

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

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  name: string;
  email: string;

  onSubmit(form: NgForm) {
    console.log(form.value); // { name: 'your name', email: 'your email' }
    console.log(form.valid); // true
  }
}

Reactive Form

Basic Form Control

import { ReactiveFormsModule } from '@angular/forms';

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

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

@Component({
  selector: 'app-name-editor',
  templateUrl: './name-editor.component.html',
  styleUrls: ['./name-editor.component.css']
})
export class NameEditorComponent {
  name = new FormControl('');
}

<label for="name">Name: </label>
<input id="name" type="text" [formControl]="name">

To display form control values

{{ name.value }}

To replace the form control value

<button (click)="update()">Update</button>

update(){
  this.name.setValue('Manthan');
}

Form Group

import { Component } from '@angular/core';
import { FormGroup, FormControl } from '@angular/forms';

@Component({
  selector: 'app-profile-editor',
  templateUrl: './profile-editor.component.html',
  styleUrls: ['./profile-editor.component.css']
})
export class ProfileEditorComponent {
  profileForm = new FormGroup({
    firstName: new FormControl(''),
    lastName: new FormControl(''),
  });
}

<form [formGroup]="profileForm" (ngSubmit)="onSubmit()">
  <div>
    <label for="first-name">First Name: </label>
    <input id="first-name" type="text" formControlName="firstName">
  </div>
  <div>
    <label for="last-name">Last Name: </label>
    <input id="last-name" type="text" formControlName="lastName">
  </div>
</form>
<p>Complete the form to enable button.</p>
<button type="submit" [disabled]="!profileForm.valid">Submit</button>

Nested form groups

import { Component } from '@angular/core';
import { FormGroup, FormControl } from '@angular/forms';

@Component({
  selector: 'app-profile-editor',
  templateUrl: './profile-editor.component.html',
  styleUrls: ['./profile-editor.component.css']
})
export class ProfileEditorComponent {
  profileForm = new FormGroup({
    firstName: new FormControl(''),
    lastName: new FormControl(''),
    address: new FormGroup({
      street: new FormControl(''),
      city: new FormControl(''),
      state: new FormControl(''),
      zip: new FormControl('')
    })
  });
}

<div formGroupName="address">
  <h2>Address</h2>

  <label for="street">Street: </label>
  <input id="street" type="text" formControlName="street">

  <label for="city">City: </label>
  <input id="city" type="text" formControlName="city">

  <label for="state">State: </label>
  <input id="state" type="text" formControlName="state">

  <label for="zip">Zip Code: </label>
  <input id="zip" type="text" formControlName="zip">
</div>

Form Data

onSubmit() {
  console.warn(this.profileForm.value);
}

<form [formGroup]="profileForm" (ngSubmit)="onSubmit()">
  <!-- form fields -->
</form>

Control State, Validity, and Error Messages

get firstName() {
  return this.profileForm.get('firstName');
}

<div *ngIf="firstName.invalid && (firstName.dirty || firstName.touched)">
  <div *ngIf="firstName.errors.required">
    First Name is required.
  </div>
</div>

Form and Data Model

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

@Component({
  selector: 'app-profile-editor',
  templateUrl: './profile-editor.component.html',
  styleUrls: ['./profile-editor.component.css']
})

export class ProfileEditorComponent {
  profileForm = this.fb.group({
    firstName: [''],
    lastName: [''],
    address: this.fb.group({
      street: [''],
      city: [''],
      state: [''],
      zip: ['']
    })
  });

  constructor(private fb: FormBuilder) { }

  onSubmit() {
    console.warn(this.profileForm.value);
  }
}

<form [formGroup]="profileForm" (ngSubmit)="onSubmit()">
  <!-- form fields -->
</form>

FormArrays

import { Component } from '@angular/core';
import { FormArray, FormBuilder } from '@angular/forms';

@Component({
  selector: 'app-profile-editor',
  templateUrl: './profile-editor.component.html',
  styleUrls: ['./profile-editor.component.css']
})

export class ProfileEditorComponent {
  profileForm = this.fb.group({
    firstName: [''],
    lastName: [''],
    address: this.fb.group({
      street: [''],
      city: [''],
      state: [''],
      zip: ['']
    }),
    aliases: this.fb.array([
      this.fb.control('')
    ])
  });

  get aliases() {
    return this.profileForm.get('aliases') as FormArray;
  }

  addAlias() {
    this.aliases.push(this.fb.control(''));
  }

  constructor(private fb: FormBuilder) { }

  onSubmit() {
    console.warn(this.profileForm.value);
  }
}

<form [formGroup]="profileForm" (ngSubmit)="onSubmit()">
  <button type="button" (click)="addAlias()">Add Alias</button>
  <div formArrayName="aliases">
    <div *ngFor="let alias of aliases.controls; let i=index">
      <input [formControlName]="i" placeholder="Alias">
    </div>
  </div>
  <button type="submit">Submit</button>
</form>

Signals

Signals serve as wrappers around values, offering the ability to notify interested consumers whenever the encapsulated value undergoes a change. These signals can accommodate a wide range of values, encompassing both basic primitives and intricate data structures.

Angular Signals

Angular Signals is a powerful system that provides detailed monitoring of state usage within an application, enabling the framework to efficiently optimize rendering updates.

import { Component, OnInit } from '@angular/core';
import { signal, computed } from '@angular/core'; // Import from '@angular/core'

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent implements OnInit {
  count = signal(0);
  doubleCount = computed(() => this.count() * 2);

  constructor() {}

  ngOnInit() {
    // Optional logging for debugging displayedCount changes
    // console.log('Displayed count changed to:', this.displayedCount());
  }

  incrementCount() {
    this.count.set(this.count() + 1);
  }

  decrementCount() {
    this.count.update((value) => Math.max(0, value - 1));
  }
}

<h1>Angular Signals Example</h1>

<button (click)="incrementCount()" style="margin-right: 10px;">Increment Count</button>
<button (click)="decrementCount()">Decrement Count</button>

<p>Count: {{ count() }}</p>
<p>Double Count: {{ doubleCount() }}</p>

Destroy Ref

The DestroyRef provider is a utility that allows Angular components to register cleanup callbacks that are executed when the component is destroyed. This is useful for cleaning up resources, such as subscriptions, timers, or other resources that need to be released when the component is no longer in use.

import { Component, OnInit, OnDestroy } from '@angular/core';
import { DestroyRef } from '@angular/core/testing';

@Component({
  selector: 'my-component',
  templateUrl: './my-component.component.html',
  styleUrls: ['./my-component.component.css']
})
export class MyComponent implements OnInit, OnDestroy {

  constructor(private destroyRef: DestroyRef) {}

  ngOnInit() {
  }

  ngOnDestroy() {
    // Register a destroy callback with the DestroyRef provider.
    this.destroyRef.register(() => {
      // Do any cleanup tasks here.
    });
  }

}

HTTP

Import HttpClient Module in Root Module -

import { NgModule } from '@angular/core';
import { HttpClientModule } from '@angular/common/http';
 
@NgModule({
    declarations: [
        AppComponent
    ],
    imports: [
        HttpClientModule
    ],
    providers: [],
    bootstrap: [AppComponent]
})
export class AppModule { }

Import Required Module in Component/Service -

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

Inject HttpClient service -

constructor(public http: HttpClient) {
}

HTTP GET

getData(){
  return this.http.get('url');
}

HTTP POST

sendData(data: any){
  return this.http.post('url', data);
}

HTTP PUT

updateData(data: any){
  return this.http.put('url', data);
}

HTTP PATCH

updateData(data: any){
  return this.http.patch('url', data);
}

HTTP DELETE

deleteData(id: string){
  return this.http.delete(`url/${id}`);
}

HTTP Interceptor

Http Interceptors are a powerful feature provided by the @angular/common/http module. They allow you to intercept and modify HTTP requests and responses in your Angular application. With interceptors, you can perform various tasks such as authentication, logging, error handling, and more. Interceptors provide a way to add global behavior to your HTTP requests and responses, making it easier to implement common functionalities across your application.

import { Injectable } from '@angular/core';
import { HttpInterceptor, HttpRequest, HttpHandler, HttpEvent } from '@angular/common/http';
import { Observable } from 'rxjs';

@Injectable()
export class MyInterceptor implements HttpInterceptor {
  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    // Modify the request before it is sent
    const modifiedRequest = request.clone({
      setHeaders: {
        'Authorization': 'Bearer my-token'
      }
    });

    // Pass the modified request to the next handler
    return next.handle(modifiedRequest);
  }
}

Using Observable

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

@Injectable({
  providedIn: 'root'
})

export class MyService {
  constructor(private http: HttpClient) {}

  getData(): Observable<any> {
    return this.http.get<any>('utl');
  }

  sendData(data: any): Observable<any> {
    return this.http.post<any>('utl', data);
  }

  updateData(data: any): Observable<any> {
    return this.http.put<any>('utl', data);
  }

  updateData(data: any): Observable<any> {
    return this.http.patch<any>('utl', data);
  }

  deleteData(id: string): Observable<any> {
    return this.http.delete<any>(`utl/${id}`);
  }
}

Options—Headers/Params

import { HttpHeaders, HttpParams } from '@angular/common/http';

const headers = new HttpHeaders({
  'Content-Type': 'application
  'Authorization': 'Bearer my-token'
});

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

this.http.get('url', { headers, params });

this.http.post('url', data, { headers, params });

this.http.put('url', data, { headers, params });

this.http.patch('url', data, { headers, params });

this.http.delete(`url/${id}`, { headers, params });

Options—Observe/Response Type

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

this.http.get('url', { observe: 'response' });

Module

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';

import { AppComponent } from './app.component';
import { AppRoutingModule } from './app-routing.module';

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

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { Page1Component } from './page-1/page-1.component';
import { Page2Component } from './page-2/page-2.component';

const routes: Routes = [
  { path: 'page-1', component: Page1Component },
  { path: 'page-2', component: Page2Component },
];

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

<h1>Routing Example</h1>
<a routerLink="page-1">Page-1</a> &nbsp;
<a routerLink="page-2">Page2-</a>
<router-outlet></router-outlet>

Lazy loading

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';

import { AppComponent } from './app.component';
import { AppRoutingModule } from './app-routing.module';

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

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

const routes: Routes = [
  {
    path: 'page-1',
    loadChildren: () =>
      import('./page-1/page-1.module').then((m) => m.Page1Module),
  },
  {
    path: 'page-2',
    loadChildren: () =>
      import('./page-2/page-2.module').then((m) => m.Page2Module),
  },
];

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

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { Page1Component } from './page-1.component';

const routes: Routes = [
  {
    path: '',
    component: Page1Component,
  },
];

@NgModule({
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule],
})
export class Page1RoutingModule {}

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { Page1Component } from './page-1.component';
import { Page1RoutingModule } from './page-1-routing.module';

@NgModule({
  imports: [CommonModule, Page1RoutingModule],
  declarations: [Page1Component],
})
export class Page1Module {}

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { Page2Component } from './page-2.component';

const routes: Routes = [
  {
    path: '',
    component: Page2Component,
  },
];

@NgModule({
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule],
})
export class Page2RoutingModule {}

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { Page2Component } from './page-2.component';
import { Page2RoutingModule } from './page-2-routing.module';

@NgModule({
  imports: [CommonModule, Page2RoutingModule],
  declarations: [Page2Component],
})
export class Page2Module {}

<h1>Lazy Loading Example</h1>
<a routerLink="page-1">Page-1</a> &nbsp;
<a routerLink="page-2">Page-2</a>
<router-outlet></router-outlet>

Certainly! Let's complete the Angular Router guide with examples for the provided sections:

Router

The Angular Router is a powerful tool that allows you to define navigation paths and routes in your application. It enables you to navigate between different components and views based on the URL path.

// app.module.ts
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';

const routes: Routes = [
  // Define your routes here
];

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

Required Route Params

To define a route with a required parameter, you can use a colon (:) followed by the parameter name. For example, in app.module.ts:

// app.module.ts
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { UserDetailsComponent } from './user-details/user-details.component';

const routes: Routes = [
  { path: 'user/:id', component: UserDetailsComponent },
  // Other routes...
];

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

Navigating in the App

To navigate to a route with a required parameter, you can use the Router service. For example, in a component:

// some-component.component.ts
import { Router } from '@angular/router';

export class SomeComponent {

  constructor(private router: Router) {}

  navigateToUserDetails(userId: number): void {
    this.router.navigate(['/user', userId]);
  }
}

Optional Route Params

To define a route with an optional parameter, you can use a question mark (?) after the parameter name. For example, in app.module.ts:

// app.module.ts
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { UserDetailsComponent } from './user-details/user-details.component';

const routes: Routes = [
  { path: 'user/:id?', component: UserDetailsComponent },
  // Other routes...
];

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

Params

To access route parameters in a component, you can use the ActivatedRoute service. For example, in a component:

// user-details.component.ts
import { ActivatedRoute } from '@angular/router';

export class UserDetailsComponent {

  constructor(private route: ActivatedRoute) {
    // Accessing route parameters
    this.route.params.subscribe(params => {
      const userId = params['id'];
      // Do something with the userId...
    });
  }
}

Services & Dependency Injection

Services -

Services in Angular are classes that are responsible for handling specific tasks or providing functionality that can be shared across multiple components. They are used to encapsulate logic and data that can be reused throughout an application.

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

@Injectable({
  providedIn: 'root'
})
export class SharedService {
  constructor() { }
}

Dependency Injection -

Dependency Injection is a design pattern in which a class receives its dependencies from an external source rather than creating them itself. In Angular, dependency injection is used to provide services to components and other services.

import { Component } from '@angular/core';
import { SharedService } from './shared.service';

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

export class MyComponent {
  constructor(private sharedService: SharedService) { }
}

Routing Module

The Angular Router module provides a powerful mechanism for defining navigation paths and routes in your application. It allows you to define routes, navigate between different components, and handle route parameters and query parameters.

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppRoutingModule } from './app-routing.module';

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

import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { CommonModule } from '@angular/common';
 
import { HomeComponent } from './home.component';
 
@NgModule({
  declarations: [HomeComponent],
  imports: [
    CommonModule,
  ],
  providers: [],
})
export class HomeModule { }

Routing Module -

The Angular Router module provides a powerful mechanism for defining navigation paths and routes in your application. It allows you to define routes, navigate between different components, and handle route parameters and query parameters.

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
 
const routes: Routes = [];
 
@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

Route Parameters

Route parameters are used to pass data to a route in Angular. They allow you to create dynamic routes that can be customized based on user input or other factors. Route parameters are defined in the route configuration and can be accessed in the component associated with the route.

There are three types of route parameters in Angular:

Path Parameters:

Path parameters are used to extract data from the URL path. They are denoted by placing a colon (":") before the parameter name in the route configuration. Path parameters are part of the route path and can be accessed in the component associated with the route. For example:

{ path: 'users/:id', component: UserComponent }

In this example, the ":id" parameter is a path parameter. The UserComponent can retrieve the value of the ":id" parameter from the URL and use it to fetch user data.

Query Parameters:

Query parameters are used to pass data as key-value pairs in the URL query string. They are denoted by placing a question mark ("?") after the route path, followed by the parameter name and value. Query parameters are not part of the route path but can be accessed in the component associated with the route. For example:

{ path: 'search', component: SearchComponent }

In this example, the SearchComponent can access query parameters like "/search?query=angular" or "/search?query=react" and use them to perform a search operation.

Optional Parameters:

Optional parameters are used to define route parameters that are not required. They are denoted by placing a question mark ("?") after the parameter name in the route configuration. Optional parameters can be present or absent in the URL, and the component associated with the route can handle both cases. For example:

{ path: 'products/:id/:category?', component: ProductComponent }

In this example, the ":category" parameter is optional. The ProductComponent can handle URLs like "/products/123" or "/products/123/electronics" based on the presence of the ":category" parameter.

Route Guards

Route guards are used to control access to routes in an Angular application. They allow you to implement logic that determines whether a user is allowed to navigate to a particular route or not. Route guards can be used to protect routes based on user authentication, authorization, or other criteria.

There are four types of route guards in Angular:

CanActivate:

The CanActivate guard is used to determine whether a route can be activated or not. It is typically used to check if a user is authenticated before allowing access to a route. The guard returns a boolean value or an Observable or Promise that resolves to a boolean value. If the guard returns true, the route is activated; if it returns false, the route is blocked.

import { Injectable } from '@angular/core';
import {
  CanActivate,
  ActivatedRouteSnapshot,
  RouterStateSnapshot,
} from '@angular/router';
import { Observable } from 'rxjs';

@Injectable()
export class AuthGuard implements CanActivate {
  canActivate(
    route: ActivatedRouteSnapshot,
    state: RouterStateSnapshot
  ): Observable<boolean> | Promise<boolean> | boolean {
    // Check if the user is authenticated
    return true; // Allow access
  }
}

CanActivateChild:

The CanActivateChild guard is similar to CanActivate but is used to protect child routes of a parent route. It is applied to the parent route configuration and is triggered when any child route is activated. The guard returns a boolean value or an Observable or Promise that resolves to a boolean value.

import { Injectable } from '@angular/core';
import {
  CanActivateChild,
  ActivatedRouteSnapshot,
  RouterStateSnapshot,
} from '@angular/router';
import { Observable } from 'rxjs';

@Injectable()
export class AuthGuard implements CanActivateChild {
  canActivateChild(
    childRoute: ActivatedRouteSnapshot,
    state: RouterStateSnapshot
  ): Observable<boolean> | Promise<boolean> | boolean {
    // Check if the user is authenticated
    return true; // Allow access
  }
}

CanDeactivate:

The CanDeactivate guard is used to determine whether a route can be deactivated or not. It is typically used to prompt the user for confirmation before leaving a route with unsaved changes. The guard returns a boolean value or an Observable or Promise that resolves to a boolean value. If the guard returns true, the route is deactivated; if it returns false, the route is not deactivated.

import { Injectable } from '@angular/core';
import {
  CanDeactivate,
  ActivatedRouteSnapshot,
  RouterStateSnapshot,
} from '@angular/router';
import { Observable } from 'rxjs';

@Injectable()
export class ConfirmDeactivateGuard implements CanDeactivate<any> {
  canDeactivate(
    component: any,
    currentRoute: ActivatedRouteSnapshot,
    currentState: RouterStateSnapshot,
    nextState?: RouterStateSnapshot
  ): Observable<boolean> | Promise<boolean> | boolean {
    // Check if the user wants to leave the route
    return confirm('Are you sure you want to leave?');
  }
}

CanLoad:

The CanLoad guard is used to determine whether a lazy-loaded module can be loaded or not. It is applied to the route configuration of a lazy-loaded module and is triggered when the module is about to be loaded. The guard returns a boolean value or an Observable or Promise that resolves to a boolean value. If the guard returns true, the module is loaded; if it returns false, the module is not loaded.

import { Injectable } from '@angular/core';
import { CanLoad, Route } from '@angular/router';
import { Observable } from 'rxjs';

@Injectable()
export class AuthGuard implements CanLoad {
  canLoad(route: Route): Observable<boolean> | Promise<boolean> | boolean {
    // Check if the user is authenticated
    return true; // Allow loading
  }
}

Observables in Angular

An observable is a class that can be used to handle asynchronous data streams. Observables are used to handle data that can arrive over time, such as data received from a server, user input, or timed events.

Unsubscribe in Angular

In Angular, managing subscriptions is crucial to avoid memory leaks and improve the performance of your application. Here are five ways to unsubscribe in Angular:

1. Using the takeUntil operator:

   • Create a subject to act as a notifier.
   • In your component, create a private property for the subject.
   • Subscribe to observables using the takeUntil operator with the subject as the parameter.
   • Emit a value on the subject when you want to unsubscribe, typically in the ngOnDestroy lifecycle hook.
   • In the ngOnDestroy hook, call complete() on the subject to stop emitting values.

   import { Component, OnDestroy } from '@angular/core';
   import { Subject } from 'rxjs';
   import { takeUntil } from 'rxjs/operators';
   
   @Component({
     selector: 'app-example',
     templateUrl: './example.component.html',
     styleUrls: ['./example.component.css']
   })
   export class ExampleComponent implements OnDestroy {
     private unsubscribe$ = new Subject<void>();
   
     ngOnInit() {
       // Subscribe to an observable
       someObservable.pipe(takeUntil(this.unsubscribe$)).subscribe((data) => {
         // Handle data
       });
     }
   
     ngOnDestroy() {
       this.unsubscribe$.next();
       this.unsubscribe$.complete();
     }
   }
   

2. Using the async pipe:

   • In your template, use the async pipe to subscribe to observables directly.
   • Angular automatically handles the subscription and unsubscription for you.
   • Ensure you don't manually subscribe to the observable in your component.

   <div>{{ someObservable$ | async }}</div>
   

3. Using the Subscription object:

   • Declare a Subscription property in your component.
   • Assign the subscription to the property when subscribing.
   • In the ngOnDestroy hook, unsubscribe from the subscription.

   import { Component, OnDestroy } from '@angular/core';
   import { Subscription } from 'rxjs';
   
   @Component({
     selector: 'app-example',
     templateUrl: './example.component.html',
     styleUrls: ['./example.component.css']
   })
   export class ExampleComponent implements OnDestroy {
     private subscription: Subscription;
   
     ngOnInit() {
       // Assign the subscription
       this.subscription = someObservable.subscribe((data) => {
         // Handle data
       });
     }
   
     ngOnDestroy() {
       // Unsubscribe from the subscription
       this.subscription.unsubscribe();
     }
   }
   

4. Using the unsubscribe operator:

   • Store the subscription in a variable.
   • Call the unsubscribe method on the subscription in the ngOnDestroy hook.

   import { Component, OnDestroy } from '@angular/core';
   
   @Component({
     selector: 'app-example',
     templateUrl: './example.component.html',
     styleUrls: ['./example.component.css']
   })
   export class ExampleComponent implements OnDestroy {
     private subscription;
   
     ngOnInit() {
       // Assign the subscription
       this.subscription = someObservable.subscribe((data) => {
         // Handle data
       });
     }
   
     ngOnDestroy() {
       // Unsubscribe from the subscription
       this.subscription.unsubscribe();
     }
   }
   

5. Using the ngOnDestroy hook and manual unsubscription:

   • Declare an array to store all the subscriptions.
   • Push the subscription to the array when subscribing.
   • Loop through the array in the ngOnDestroy hook and unsubscribe from each subscription.

   import { Component, OnDestroy } from '@angular/core';
   import { Subscription } from 'rxjs';
   
   @Component({
     selector: 'app-example',
     templateUrl: './example.component.html',
     styleUrls: ['./example.component.css']
   })
   export class ExampleComponent implements OnDestroy {
     private subscriptions: Subscription[] = [];
   
     ngOnInit() {
       // Push the subscription to the array
       this.subscriptions.push(someObservable.subscribe((data) => {
         // Handle data
       }));
     }
   
     ngOnDestroy() {
       // Unsubscribe from all subscriptions
       this.subscriptions.forEach(subscription => subscription.unsubscribe());
     }
   }
   

Renderer2

Renderer2 is a utility class that provides methods to manipulate and interact with the DOM (Document Object Model). It is used to perform operations such as creating, modifying, and removing elements, applying styles, and listening to events.

import { Component, Renderer2, ElementRef } from '@angular/core';

@Component({
  selector: 'app-example',
  template: `
    <button (click)="changeColor()">Change Color</button>
  `
})
export class ExampleComponent {
  constructor(private renderer: Renderer2, private el: ElementRef) { }

  changeColor() {
    const button = this.el.nativeElement.querySelector('button');
    this.renderer.setStyle(button, 'background-color', 'red');
  }
}

Standalone Components

A standalone component is a type of component which is not part of any Angular module. It provides a simplified way to build Angular applications.

JIT

Just-in-Time (JIT) is a type of compilation that compiles your app in the browser at runtime. This is the default compilation mode for Angular applications.

Advantages of JIT

• Faster development cycle as changes can be seen immediately.
• No build step required during development.
• More flexible for dynamic template generation.

AOT

Ahead-of-Time (AOT) is a type of compilation that compiles your app at build time. This mode is used to pre-compile your Angular application before deployment.

Advantages of AOT

• Faster startup times as the browser only needs to execute the compiled code.
• Improved performance due to optimized and pre-compiled templates.
• Better security as the templates are already compiled and validated before deployment.
• Smaller bundle sizes since the templates are not included.

JIT vs AOT

Differences between AOT and JIT

Deferrable Views

Deferrable views can be used in component template to defer the loading of select dependencies within that template.

@defer {
  <large-component />
}

Angular Universal

Angular Universal is a server-side rendering module for Angular applications in various scenarios. This is a community driven project and available under @angular/platform-server package.

// create the application
ng add @nguniversal/express-engine

//run the application
npm run dev:ssr

Angular Animations

Angular's animation system is built on CSS functionality in order to animate any property that the browser considers animatable. These properties includes positions, sizes, transforms, colors, borders etc. The Angular modules for animations are @angular/animations and @angular/platform-browser.

Meta tags

Title Service

import { BrowserModule, Title } from '@angular/platform-browser';

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

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

export class TitleComponent implements OnInit {
  constructor(private title:Title) { }
}

ngOnInit() {
  this.title.setTitle("Learn Angular")
}

import { Component, OnInit } from '@angular/core';
import { Title, MetaDefinition } from '@angular/platform-browser';
 
@Component({
  template: `<h1>App Component</h1>`
})
export class AppComponent implements OnInit {
  title = 'App Component';
 
  constructor(private title:Title){
  }
 
  ngOnInit() {
    this.title.setTitle("Learn Angular")
  }
 
}

Title Service Example

// app.module.ts
import { BrowserModule, Title } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
 
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { HomeComponent } from './home.component';
 
@NgModule({
  declarations: [
    AppComponent, HomeComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule
  ],
  providers: [Title],
  bootstrap: [AppComponent]
})
export class AppModule { }

// app-routing.module.ts
import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { HomeComponent } from './home.component';

const routes: Routes = [
  {path: 'home', component:HomeComponent},
];
 
@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

// app.component.ts
import { Component } from '@angular/core';
import { Title } from '@angular/platform-browser';
 
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'Title Service Example';
 
  constructor(private titleService:Title) {
  }
 
  ngOnInit() {
    this.titleService.setTitle(this.title);
  }
}

<!-- app.component.html -->
<h1>Title Service Example</h1>
 
<ul>
  <li><a [routerLink]="['/home']">Home</a> </li>
</ul>
 
<router-outlet></router-outlet>

// home.component.ts
import { Component, OnInit } from '@angular/core';
import { Title } from '@angular/platform-browser';

@Component({
  template: `<h1>Home Component</h1>`
})
export class HomeComponent implements OnInit {
  title = 'Home Component Title';
 
  constructor(private titleService:Title){
  }
 
  ngOnInit() {
    this.titleService.setTitle(this.title);
  }
 
}

Dynamic Title

// app.module.ts
import { BrowserModule, Title } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
 
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { HomeComponent } from './home.component';
 
@NgModule({
  declarations: [
    AppComponent, HomeComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule
  ],
  providers: [Title],
  bootstrap: [AppComponent]
})
export class AppModule { }

// app-routing.module.ts
import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { HomeComponent } from './home.component';
import { PParentComponent } from './parent.component';
import { ChildComponent } from './child.component';

const routes: Routes = [
  {path: '', component:HomeComponent, data : {title:'Title for Home Component'}},
  {path: 'parent', component:ParentComponent, data : {title:'Title for Parent Component'},
    children: [
      { path: 'child', component:ChildComponent, data : {title:'Title for Child Component'}}
    ]
  },
];
 
@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }

// app.component.ts
import { Component } from '@angular/core';
import { Title } from '@angular/platform-browser';
import { Router, NavigationEnd, ActivatedRoute } from '@angular/router';
import { filter, map } from 'rxjs/operators';
 
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {

 constructor(
  private router: Router,
  private activatedRoute: ActivatedRoute,
  private titleService: Title
  ) { }
 
  ngOnInit() {
 
    this.router.events.pipe(
        filter(event => event instanceof NavigationEnd),
      )
      .subscribe(() => {
 
        var rt = this.getChild(this.activatedRoute)
 
        rt.data.subscribe(data => {
          console.log(data);
          this.titleService.setTitle(data.title)})
      })
 
  }
 
  getChild(activatedRoute: ActivatedRoute) {
    if (activatedRoute.firstChild) {
      return this.getChild(activatedRoute.firstChild);
    } else {
      return activatedRoute;
    }
 
  }
}

<!-- app.component.html -->
<h1>Dynamic Title Example</h1>
 
<ul>
  <li><a routerLink="">Home</a> </li>
  <li><a [routerLink]="['/parent']">Parent</a> </li>
  <li><a [routerLink]="['/child']">Child</a> </li>
</ul>
 
<router-outlet></router-outlet>

// home.component.ts
import { Component, OnInit } from '@angular/core';

@Component({
  template: `<h1>Home Component</h1>`
})
export class HomeComponent implements OnInit {
 
  constructor(){
  }
 
  ngOnInit() {
  }
 
}

// parent.component.ts
import { Component, OnInit } from '@angular/core';

@Component({
  template: `<h1>Parent Component</h1>
  <router-outlet></router-outlet>
  `
})
export class ParentComponent implements OnInit {
 
  constructor(){
  }
 
  ngOnInit() {
  }
 
}

// child.component.ts
import { Component, OnInit } from '@angular/core';

@Component({
  template: `<h1>Child Component</h1>`
})
export class ChildComponent implements OnInit {
 
  constructor(){
  }
 
  ngOnInit() {
  }
 
}

Meta Service

import { BrowserModule, Meta } from '@angular/platform-browser';

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

import { Component, OnInit } from '@angular/core';
import { Meta, MetaDefinition } from '@angular/platform-browser';
 
@Component({
  template: `<h1>App Component</h1>`
})
export class AppComponent implements OnInit {
  title = 'App Component';
 
  constructor(private metaService:Meta){
  }
 
  ngOnInit() {
    this.metaService.addTag( { name:'description',content:"Article Description"});
  }
 
}

Adding Tags with addTag() & addTags()

this.metaService.addTag( { name:'description',content:"Article Description"});

this.metaService.addTag( 
  { name: 'description', content: 'Article Description' },
  { name: 'robots', content: 'index,follow' },
  { property: 'og:title', content: 'Content Title for social media' }
);

Reading the Tags with getTag()

this.metaService.getTag("name='description'")

Update the Tag with updateTag()

this.metaService.updateTag( { name:'robots', content:'index, nofoloow'},"name='robots'");

Removing the Tag with removeTag()

this.metaService.removeTag("name='robots'");

Deploying an Angular Application

CLI Commands

Installing Angular CLI

npm install -g @angular/cli

Help

ng help

Check version

ng version

Create, build, and serve a new, basic Angular project cli command

ng new my-first-project
cd my-first-project
ng serve

Generating new application

ng new app-name

Create new app without installing cli

npm init @angular app-name

Component

ng g c component-name
ng generate component component-name

Adding External libraries

ng add

Build

ng build

Running project

ng serve

Run project on particular port

ng serve --port=portname
// example
ng serve --port=3000

Run project and open the url in default browser

ng  serve --open

Update

ng update

Directive

ng generate directive component-name
ng g directive component-name

Module

ng generate module module-name
ng g m module-name

Service

ng generate service component-name
ng g service component-name

Routing Module

ng g module module-name --routing
ng g m module-name --routing

Component with module, routing module

ng generate module component-name --route component-name --module app.module

Pipe

ng g pipe pipe-name

Enum

ng g enum some-enum

Class

ng g cl my-class

Interface

ng g interface my-interface

Guard

ng g guard guard-name

Multiple Projects in one Angular App

ng generate application sub-app-name

ng new app-name --create-application=false

Generate environments

ng generate environments

Version compatibility

Imports

Angular Core

import { Component } from '@angular/core'; // Component decorator
import { NgModule } from '@angular/core'; // NgModule decorator
import { RouterModule, Routes } from '@angular/router'; // Routing module
import { FormsModule } from '@angular/forms'; // Forms module
import { ReactiveFormsModule } from '@angular/forms'; // Reactive forms module
import { HttpClientModule } from '@angular/common/http'; // HTTP client module
import { BrowserModule } from '@angular/platform-browser'; // Browser module
import { BrowserAnimationsModule } from '@angular/platform-browser/animations'; // Animations module
import { CommonModule } from '@angular/common'; // Common module
import { NgModel } from '@angular/forms'; // NgModel directive
import { NgForm } from '@angular/forms'; // NgForm directive
import { FormGroup, FormControl, Validators } from '@angular/forms'; // Form group, form control, validators
import { HttpClient } from '@angular/common/http'; // HTTP client
import { ActivatedRoute } from '@angular/router'; // Route parameters
import { Router } from '@angular/router'; // Router service
import { Title } from '@angular/platform-browser'; // Title service
import { Meta } from '@angular/platform-browser'; // Meta service
import { Renderer2 } from '@angular/core'; // Renderer2 service
import { ElementRef } from '@angular/core'; // ElementRef service
import { ViewChild } from '@angular/core'; // ViewChild decorator
import { ViewContainerRef } from '@angular/core'; // ViewContainerRef service
import { ComponentFactoryResolver } from '@angular/core'; // ComponentFactoryResolver service
import { ChangeDetectorRef } from '@angular/core'; // ChangeDetectorRef service
import { Pipe, PipeTransform } from '@angular/core'; // Pipe decorator, PipeTransform interface
import { Injectable } from '@angular/core'; // Injectable decorator
import { EventEmitter } from '@angular/core'; // EventEmitter class
import { Output } from '@angular/core'; // Output decorator
import { Input } from '@angular/core'; // Input decorator
import { HostListener } from '@angular/core'; // HostListener decorator
import { HostBinding } from '@angular/core';  // HostBinding decorator
import { ContentChild } from '@angular/core'; // ContentChild decorator
import { ContentChildren } from '@angular/core';  // ContentChildren decorator
import { QueryList } from '@angular/core';  // QueryList class
import { AfterContentInit } from '@angular/core'; // AfterContentInit interface
import { AfterContentChecked } from '@angular/core';  // AfterContentChecked interface
import { AfterViewInit } from '@angular/core';  // AfterViewInit interface
import { AfterViewChecked } from '@angular/core'; // AfterViewChecked interface
import { OnInit } from '@angular/core'; // OnInit interface
import { OnDestroy } from '@angular/core';  // OnDestroy interface
import { OnChanges } from '@angular/core';  // OnChanges interface
import { SimpleChanges } from '@angular/core';  // SimpleChanges class
import { DoCheck } from '@angular/core';  // DoCheck interface
import { KeyValueDiffers } from '@angular/core';  // KeyValueDiffers service
import { KeyValueDiffer } from '@angular/core'; // KeyValueDiffer interface
import { KeyValueChanges } from '@angular/core';  // KeyValueChanges interface
import { KeyValueChangeRecord } from '@angular/core'; // KeyValueChangeRecord interface 
import { IterableDiffers } from '@angular/core';  // IterableDiffers service
import { IterableDiffer } from '@angular/core'; // IterableDiffer interface
import { IterableChanges } from '@angular/core';  // IterableChanges interface
import { IterableChangeRecord } from '@angular/core'; // IterableChangeRecord interface
import { ChangeDetectionStrategy } from '@angular/core';  // ChangeDetectionStrategy enum
import { ChangeDetectorRef } from '@angular/core';  // ChangeDetectorRef service
import { NgZone } from '@angular/core'; // NgZone service
import { ApplicationRef } from '@angular/core'; // ApplicationRef service
import { ComponentRef } from '@angular/core'; // ComponentRef class
import { ComponentFactory } from '@angular/core'; // ComponentFactory class
import { ComponentFactoryResolver } from '@angular/core'; // ComponentFactoryResolver service
import { ViewContainerRef } from '@angular/core'; // ViewContainerRef service
import { TemplateRef } from '@angular/core';  // TemplateRef class
import { EmbeddedViewRef } from '@angular/core';  // EmbeddedViewRef class

Angular Material

import { MatDialog } from '@angular/material/dialog';
import { MatSnackBar } from '@angular/material/snack-bar';
import { MatTableDataSource } from '@angular/material/table';
import { MatPaginator } from '@angular/material/paginator';
import { MatSort } from '@angular/material/sort';
import { MatFormFieldModule } from '@angular/material/form-field';
import { MatButtonModule } from '@angular/material/button';
import { MatInputModule } from '@angular/material/input';
import { MatIconModule } from '@angular/material/icon';
import { MatToolbarModule } from '@angular/material/toolbar';
import { MatMenuModule } from '@angular/material/menu';
import { MatSelectModule } from '@angular/material/select';
import { MatCheckboxModule } from '@angular/material/checkbox';
import { MatDatepickerModule } from '@angular/material/datepicker';
import { MatNativeDateModule } from '@angular/material/core';
import { MatCardModule } from '@angular/material/card';
import { MatProgressSpinnerModule } from '@angular/material/progress-spinner';
import { MatProgressBarModule } from '@angular/material/progress-bar';
import { MatDialogModule } from '@angular/material/dialog';
import { MatTooltipModule } from '@angular/material/tooltip';
import { MatRadioModule } from '@angular/material/radio';
import { MatSlideToggleModule } from '@angular/material/slide-toggle';
import { MatTabsModule } from '@angular/material/tabs';
import { MatSidenavModule } from '@angular/material/sidenav';
import { MatExpansionModule } from '@angular/material/expansion';
import { MatGridListModule } from '@angular/material/grid-list';
import { MatAutocompleteModule } from '@angular/material/autocomplete';
import { MatChipsModule } from '@angular/material/chips';
import { MatListModule } from '@angular/material/list';
import { MatStepperModule } from '@angular/material/stepper';
import { MatBadgeModule } from '@angular/material/badge';
import { MatBottomSheetModule } from '@angular/material/bottom-sheet';
import { MatButtonToggleModule } from '@angular/material/button-toggle'; 
import { MatDividerModule } from '@angular/material/divider';
import { MatPaginatorModule } from '@angular/material/paginator';
import { MatRippleModule } from '@angular/material/core';
import { MatSliderModule } from '@angular/material/slider';
import { MatSnackBarModule } from '@angular/material/snack-bar';
import { MatSortModule } from '@angular/material/sort';
import { MatTreeModule } from '@angular/material/tree';

RxJS

import { Observable } from 'rxjs/Observable';
import { Subject } from 'rxjs/Subject';
import { BehaviorSubject } from 'rxjs/BehaviorSubject';
import { ReplaySubject } from 'rxjs/ReplaySubject';
import { AsyncSubject } from 'rxjs/AsyncSubject';
import { Subscription } from 'rxjs/Subscription';
import { from } from 'rxjs';
import { fromEvent } from 'rxjs';
import { interval } from 'rxjs';
import { timer } from 'rxjs';
import { merge } from 'rxjs';
import { zip } from 'rxjs';
import { combineLatest } from 'rxjs';
import { concat } from 'rxjs';
import { forkJoin } from 'rxjs';
import { race } from 'rxjs';
import { map } from 'rxjs/operators';
import { filter } from 'rxjs/operators';
import { reduce } from 'rxjs/operators';
import { tap } from 'rxjs/operators';
import { catchError } from 'rxjs/operators';
import { retry } from 'rxjs/operators';
import { switchMap } from 'rxjs/operators';
import { take } from 'rxjs/operators';
import { debounceTime } from 'rxjs/operators';
import { distinctUntilChanged } from 'rxjs/operators';
import { scan } from 'rxjs/operators';
import { mergeMap } from 'rxjs/operators';
import { exhaustMap } from 'rxjs/operators';
import { concatMap } from 'rxjs/operators';
import { takeUntil } from 'rxjs/operators';
import { finalize } from 'rxjs/operators';
import { share } from 'rxjs/operators';
import { shareReplay } from 'rxjs/operators';
import { buffer } from 'rxjs/operators';
import { bufferCount } from 'rxjs/operators';
import { bufferTime } from 'rxjs/operators';
import { bufferToggle } from 'rxjs/operators';
import { bufferWhen } from 'rxjs/operators';
import { combineAll } from 'rxjs/operators';
import { concatAll } from 'rxjs/operators';
import { count } from 'rxjs/operators';
import { endWith } from 'rxjs/operators';
import { every } from 'rxjs/operators';
import { exhaust } from 'rxjs/operators';
import { first } from 'rxjs/operators';
import { groupBy } from 'rxjs/operators';
import { ignoreElements } from 'rxjs/operators';
import { isEmpty } from 'rxjs/operators';
import { last } from 'rxjs/operators';
import { max } from 'rxjs/operators';
import { mergeAll } from 'rxjs/operators';
import { min } from 'rxjs/operators';
import { pairwise } from 'rxjs/operators';
import { partition } from 'rxjs/operators';
import { pluck } from 'rxjs/operators';

Firebase

import { AngularFireModule } from "@angular/fire/compat";
import { AngularFireAuthModule } from "@angular/fire/compat/auth";
import { AngularFireStorageModule } from '@angular/fire/compat/storage';
import { AngularFirestoreModule } from '@angular/fire/compat/firestore';
import { AngularFireDatabaseModule } from '@angular/fire/compat/database';
import { AngularFireStorage } from '@angular/fire/storage';

import { AngularFireModule } from '@angular/fire';
import { AngularFireAuthModule } from '@angular/fire/auth';
import { AngularFireDatabaseModule } from '@angular/fire/database';
import { AngularFireStorageModule } from '@angular/fire/storage';
import { AngularFirestoreModule } from '@angular/fire/firestore';
import { AngularFireFunctionsModule } from '@angular/fire/functions';
import { AngularFireMessagingModule } from '@angular/fire/messaging';
import { AngularFirePerformanceModule } from '@angular/fire/performance';
import { AngularFireRemoteConfigModule } from '@angular/fire/remote-config';
import { AngularFireAnalyticsModule } from '@angular/fire/analytics';
import { AngularFireAuthGuardModule } from '@angular/fire/auth-guard';

TypeScript

TypeScript is JavaScript with syntax for types. TypeScript is a superset of JavaScript that compiles to plain JavaScript. It is developed and maintained by Microsoft.

Rxjs

Reactive Extensions Library for JavaScript - RxJS is a library for reactive programming using Observables, to make it easier to compose asynchronous or callback-based code.

NgRx

NgRx is a Reactive libraries for Angular. It provides state management, side effects, and route handling. It is inspired by Redux. It is a set of Angular libraries to help manage state at scale in Angular applications.

NgXS

NgXS is a state management pattern + library for Angular. It acts as a single source of truth for your application's state, providing simple rules for predictable state mutations.

Learn more from GitHub Repositories

• Awesomw Angular
• Angular JumpStart
• Angular Interview Questions by Sudheerj
• Angular Learning Resources
• CodAffection
• Bezkoder
• Angular Interview Questions by Yonet
• Angular Basics ( v14.x )

Learn more from Websites

• Official Documentation
• Tektutorialshub
• W3School
• GeeksForGeeks
• DevDocs
• Freecodecamp
• Javatpoint
• Tutorialspoint
• Udemy
• YouTube
• Stackoverflow
• NX Blog
• Indepthdev
• Angular University
• Bezkoder

Learn more from Books

• Angular From Theory To Practice
• Angular in Action
• Ng-Book: The Complete Guide to Angular
• Pro Angular 6
• Beginning Angular with Typescript
• Angular 6 for Enterprise-Ready Web Applications
• ASP.NET Core 2 and Angular 5
• Angular Up & Running
• Codecraft
• Rangle.io
• Angular 2 Succinctly
• Angular2Book
• Learning Angular: A no-nonsense guide to building web applications with Angular 15, 4th Edition

Learn from YouTube Channels

• Freecodecamp
• Programming With Mosh
• Angular University
• Traversy Media
• Code With Harry
• Fireship
• Academind
• Decoded Frontend
• Brandon Roberts
• ARC Tutorials
• Edureka
• Simplilearn
• Joshua Morony
• Codevolution
• Code Step By Step
• UX Trendz
• Devstackr
• David Acosta
• Testy Codiez
• CodAffection
• Techsith

Learn More From Blogs Sites

• Freecodecamp
• Medium
• Dev.to
• Hashnode
• Angular Blog
• Angular In Depth
• Angular University

List of Online Editors/Compiler for Angular

• Stackblitz
• CodeSandbox
• Plunker

List of Twitter Users to Follow

• Mosh
• Minko Gechev
• Todd Motto
• Deborah Kurata
• John Papa
• Dan Wahlin
• Maximilian Schwarzmüller
• Wes Bos
• Tracy Lee | ladyleet
• Shai Reznik
• Victor Savkin
• Stephen Fluin
• Juri Strumpflohner

List of LinkedIn Users to Follow

• Kevin Kreuzer
• Aristeidis Bampakos
• Dmytro Mezhenskyi
• Santosh Yadav
• Tomas Trajan
• Marko Stanimirović
• Teja Gandhamu
• Santosh Yadav
• Juri Strumpflohner
• Minko Gechev
• Todd Motto
• Deborah Kurata

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Angular
• Stackblitz

Connect with me

• Twitter
• LinkedIn
• Facebook
• Instagram
• YouTube
• GitHub

Support

If you like this learning repository and find it useful, consider buying me a coffee or sponsoring me through the GitHub Sponsor. Your support will help me to continue and bring more exciting projects. Thank you!

Show your support by 🌟 the repository.