Showing posts with label Angular. Show all posts

How To Add Font Awesome in Angular?

December 28, 2025 No comments 0

Icons play a crucial role in building modern and user-friendly web applications. Font Awesome is one of the most popular icon libraries, and Angular provides multiple clean ways to integrate it.

In this article, you’ll learn all the correct ways to add Font Awesome in Angular, when to use each approach, and common mistakes to avoid.

Prerequisites

Before starting, make sure:

The Angular project is already created
Node.js and npm are installed
Basic Angular knowledge (components & templates)

Method 1: Add Font Awesome Using CDN.

Font Awesome CDN method works by loading Font Awesome’s CSS file directly from the internet into your Angular app. This is the fastest method and best for:

Demos
Small projects
Prototypes

Step 1: Add Font Awesome CDN to the index.html page in Angular.

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8" />
  <title>AngularApp</title>

  <!-- Font Awesome CDN -->
  <link
    rel="stylesheet"
    href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.5.1/css/all.min.css"
  />
</head>
<body>
  <app-root></app-root>
</body>
</html>

Step 2: Use Icons in Component HTML.

<i class="fa-solid fa-user"></i>
<i class="fa-solid fa-envelope"></i>
<i class="fa-solid fa-lock"></i>

✅ Pros

No installation required
Very easy setup

❌ Cons

External dependency
Not ideal for production or offline builds

Method 2: Install Font Awesome via npm.

This is the most commonly used and professional approach.

Step 1: Install Font Awesome.

npm install @fortawesome/fontawesome-free

Step 2: Add CSS to angular.json

"styles": [
  "node_modules/@fortawesome/fontawesome-free/css/all.min.css",
  "src/styles.css"
]

Note: Always add Font Awesome before your custom styles.

Step 3: Restart the Angular Server.

ng serve

Step 4: Use Icons in Template.

<i class="fa-solid fa-user"></i>
<i class="fa-regular fa-bell"></i>
<i class="fa-brands fa-github"></i>

✅ Pros

Works offline
Version-controlled
Production-ready

❌ Cons

Loads entire icon set (slightly larger bundle)

Adding Font Awesome in Angular is simple once you understand which approach fits your use case.

Start with npm-based CSS, and move to Angular Font Awesome for scalable applications.

Angular

How To Check, Install and Update Angular on Your System.

Probin Kumar Sah

October 01, 2025 No comments 0

Angular, powered by the Angular CLI (Command Line Interface), is a robust platform for building scalable web applications. The CLI is your essential tool, allowing you to scaffold, develop, test, and deploy your Angular projects right from your command shell. As an Angular Expert, I'll guide you through the crucial steps of managing the Angular CLI on your system: checking the current version, installing it for the first time, and keeping it up-to-date.

Prerequisites: The Node.js and npm Foundation

Before you can work with the Angular CLI, you must have Node.js and its package manager, npm (Node Package Manager), installed on your system. Angular CLI is an npm package and uses Node.js to run its tooling outside the browser.

Check Your Node.js and npm Versions

Open your terminal or command prompt and run the following commands:

Step 1: Check Node.js version:

node -v

Step 2: Check npm version:

npm -v

Angular typically requires an active LTS (Long Term Support) or maintenance LTS version of Node.js. If you don't have Node.js or if your version is outdated, visit the official

Node.js website

to download and install the latest LTS version.

How to Check Your Angular CLI Version.

Knowing your current Angular CLI version is the first step to ensuring you are working with the expected features and compatibility.

Check Global Angular CLI Version.

The most straightforward way to check your globally installed Angular CLI version is to use the ng version command in your terminal.

ng version
# or
ng v

Example Output:

The output will display the versions of the Angular CLI, Node.js, and several key Angular packages (if run inside an Angular project, it will show project-specific versions as well).

Check Project-Specific Angular Version

If you are inside an Angular project folder, running ng version will give you a detailed breakdown of the Angular packages installed locally in that project (e.g., @angular/core, @angular/common, etc.). This is important because a project's local dependencies can sometimes differ from your global CLI version. You can also inspect the package.json file in your project root to see all your Angular dependency versions.

How To Install the Angular CLI.

If you've never installed the Angular CLI before, you'll need to install it globally using npm. This makes the ng command available from any location in your command line.

Execute the following command in your terminal:

npm install -g @angular/cli

npm install: The command to install npm packages.
-g: The flag for installing the package globally.
@angular/cli: The name of the Angular CLI package.

While generally not recommended unless you have a specific requirement, you can install a particular major version of the CLI by appending the version number:

npm install -g @angular/cli@17
# This will install the latest available version in the Angular v17 line

After the installation completes, run the check command again to verify that the latest CLI has been successfully installed:

ng version

How To Update Angular (CLI and Project).

The Angular team frequently releases new versions, often including performance improvements, new features, and bug fixes. Keeping both your global Angular CLI and your Angular project packages up-to-date is best practice.

To get the latest global version of the CLI, simply re-run the install command, optionally specifying the @latest tag:

npm install -g @angular/cli@latest

This command will uninstall the old global version and install the most recent stable release.

Note: While updating you might get a warning message show below. We usualy get this warning when your Node.Js version is not matching with latest required of Angular. You need to install the updated version of Node.Js in your system to fix this error.

Update Local Project Packages.

Updating your Angular project itself is slightly more complex, especially when jumping between major versions (e.g., from Angular 16 to Angular 17). Angular provides a powerful command, ng update, designed to automate this process.

1. Check for Available Updates: The first step is to see what updates are available for your current project:

ng update

This command lists packages that have available updates, along with a recommendation on which packages to update first.

2. Run the Primary Update: For major versions, it is recommended to update the core packages (@angular/core and @angular/cli) first:

ng update @angular/core @angular/cli

The ng update command is smart: it updates packages and runs migration schematics to automatically update your code to match the new APIs and conventions, minimizing manual effort.

3. Update Other Dependencies: After updating the core packages, you may need to update other libraries and tools, such as Angular Material or other third-party libraries:

ng update @angular/material

Pro Tip: For a detailed, step-by-step guide tailored to your specific current and target versions, always consult the official Angular Update Guide on the Angular website. It provides customized instructions and highlights manual changes that may be necessary, especially for major version upgrades (e.g., from v15 to v17).

Conclusion.

The Angular CLI is a cornerstone of the Angular development experience. By mastering the simple commands to check (ng version), install (npm install -g @angular/cli), and update (ng update), you ensure your development environment is modern, efficient, and ready to leverage the latest features Angular has to offer.

Angular TypeScript

How To Resolve Circular Dependency Error in Angular.

Probin Kumar Sah

September 29, 2025 No comments 0

In Angular, sometimes your code gets stuck, like two friends asking each other the same question but never answering. This problem is called a Circular Dependency. It happens when two (or more) parts of your code depend on each other in a loop, and Angular doesn’t know where to start.

Before understanding the process of resolving Circular Dependency, let's first understand what Dependency is and why it is so important in building any software application.

What is Dependency?

In programming, a dependency is a relationship where one piece of code relies on another to function correctly. This is a fundamental concept in software development, as modern applications are rarely built from scratch. Instead, developers reuse existing, pre-written code in the form of libraries, frameworks, or modules.

Dependency Example:

Think of baking a cake. To make the cake (your code), you need flour, sugar, and eggs (dependencies). You don't have to create the flour or sugar yourself; you buy them from a store (like downloading from a library). Without these ingredients, you can't bake the cake. Your cake recipe depends on the ingredients.

In software, dependencies work the same way:

A component (like a button on a web page) might depend on a styling library to make it look good.
A service that handles user login might depend on a database library to interact with the database.

This dependency relationship is usually one-way. The button needs the styling library, but the styling library doesn't need to know anything about the button. The login service needs the database library, but the database library doesn't need to know anything about the login service.

When you have a dependency, if the code you're depending on changes or is unavailable, your code will likely fail. This is why managing dependencies is a crucial part of software development.

Understanding this one-way relationship is the key to grasping why a circular dependency, where two components depend on each other, is so problematic.

What is Circular Dependency?

A circular dependency occurs when two or more components, modules, or services depend on each other, creating a closed loop. This prevents them from being properly initialized or compiled because each one is waiting for the other to be ready first.

Imagine two people, Alice and Bob.

Alice says, "I can't start my project until Bob gives me his budget report."
Bob says, "I can't finish my budget report until Alice starts her project, so I can get the final numbers."

They are stuck in an eternal loop. Alice needs Bob's input to begin, and Bob needs Alice's progress to finish. Neither can move forward, and the project is deadlocked. This is a circular dependency.

In a software application, the same principle applies. For example, in a codebase:

UserService needs to call a method in PaymentService to process a transaction.
PaymentService needs to access a user's details, which it gets by calling a method in UserService.

This creates a tight coupling where UserService depends on PaymentService, and PaymentService depends on UserService. The system can't decide which service to initialize first, leading to errors. This anti-pattern indicates a poor design that makes the code difficult to maintain, test, and reuse.

Let's recreate circular dependency to understand the exact condition and how to resolve it.

Example of Circular Dependency in Angular.

user.service.ts

// user.service.ts
import { Injectable } from '@angular/core';
import { PaymentService } from './payment.service';

@Injectable({ providedIn: 'root' })
export class UserService {
  constructor(private paymentService: PaymentService) {}

  getUserDetails(userId: number) {
    console.log("Fetching user details for", userId);

    // Oh no ❌ UserService is calling PaymentService
    this.paymentService.getPaymentsForUser(userId);
  }
}

payment.service.ts

// payment.service.ts
import { Injectable } from '@angular/core';
import { UserService } from './user.service';

@Injectable({ providedIn: 'root' })
export class PaymentService {
  constructor(private userService: UserService) {}

  getPaymentsForUser(userId: number) {
    console.log("Fetching payments for", userId);

    // Oh no ❌ PaymentService is calling UserService again
    this.userService.getUserDetails(userId);
  }
}

This Angular code is trying to create a userService, but userService needs PaymentService. Then Angular tries to create PaymentService, but PaymentService needs userService. Angular goes back to create userService...and this cycle never ends. This is a circular dependency.

userService -> PaymentService -> userService

Error: Circular dependency in DI detected for UserService

We need to break the direct cycle by introducing a shared service or event mediator. Let's learn both methods one by one.

Method 1: Resolve Circular Dependency Using Shared Service.

This is the most popular and easiest way to break circular dependency by moving the common logic into a third service that both can use.

Here are a few simple steps that you need to follow:

1. Identify the code that causes a circular reference.

2. Create a new independent service.

3. Inject this service into both classes instead of injecting each other.

Fix Example:

This is a mediator service that holds the shared logic.

// data.service.ts
@Injectable({ providedIn: 'root' })
export class DataService {
  getUserDetails(userId: string) {
    console.log("Fetching user details:", userId);
  }

  getPaymentsForUser(userId: string) {
    console.log("Fetching payments for user:", userId);
  }
}

This is the modified userService after introducing the shared service.

// user.service.ts
@Injectable({ providedIn: 'root' })
export class UserService {
  constructor(private data: DataService) {}

  getUserDetails(userId: string) {
    this.data.getUserDetails(userId);
  }
}

This is the modified PaymentService after introducing the shared service.

// payment.service.ts
@Injectable({ providedIn: 'root' })
export class PaymentService {
  constructor(private data: DataService) {}

  getPaymentsForUser(userId: string) {
    this.data.getPaymentsForUser(userId);
  }
}

Now both services depend only on DataService → no cycle. This is cleaner and easier to maintain.

Method 2: Use forwardRef().

If the dependency is truly unavoidable (say, PaymentService must call UserService directly), we can use forwardRef().

How does forwardRef() Work?

In Angular, when you create a service or class, Angular tries to resolve all dependencies immediately at runtime.
But in circular dependency cases, one class might not be defined yet when Angular tries to use it.

👉 forwardRef() is a helper function that tells Angular:

“Don’t try to resolve this dependency right now — wait until everything is defined, and then resolve it.”

Fix Example:

// user.service.ts
@Injectable({ providedIn: 'root' })
export class UserService {
  constructor(
    @Inject(forwardRef(() => PaymentService)) private payment: PaymentService
  ) {}

  getUserDetails(userId: string) {
    console.log("Fetching user details:", userId);
    this.payment.getPaymentsForUser(userId);
  }
}

// payment.service.ts
@Injectable({ providedIn: 'root' })
export class PaymentService {
  constructor(
    @Inject(forwardRef(() => UserService)) private user: UserService
  ) {}

  getPaymentsForUser(userId: string) {
    console.log("Fetching payments for user:", userId);
    this.user.getUserDetails(userId);
  }
}

Now Angular delays resolution until both services are defined.

The circular error is avoided, but if you keep calling each other directly, there’s still a risk of infinite recursion, so use it carefully.

Angular

Types of Data Binding in Angular.

Probin Kumar Sah

July 16, 2025 No comments 0

Data binding in Angular is a powerful feature that allows you to synchronize data between the component and the view. It is used to ensure that the user interface reflects the current state of the data model and vice versa. This synchronization helps in creating dynamic and interactive applications.

There are four main types of data binding in Angular:

Interpolation
Property Binding
Event Binding
Two-Way Binding

1. Interpolation

Why it's used: Interpolation allows you to display component data in the template. It is a simple way to bind data from the component to the view.

Example:

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

@Component({
  selector: 'app-interpolation',
  template: `<h1>{{ title }}</h1>`
})
export class InterpolationComponent {
  title: string = 'Hello, Angular!';
}

Use Case: Use interpolation when you want to display a string or a number from the component in the template.

2. Property Binding

Why it's used: Property binding allows you to bind component properties to the properties of HTML elements. This is useful for dynamically setting attributes or properties based on the component's state.

Example:

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

@Component({
  selector: 'app-property-binding',
  template: `<img [src]="imageUrl" alt="Image">`
})
export class PropertyBindingComponent {
  imageUrl: string = 'https://example.com/image.png';
}

Use Case: Use property binding when you need to set properties of HTML elements, such as src, disabled, or value, based on the component's data.

3. Event Binding

Why it's used: Event binding allows you to listen to events emitted by DOM elements and execute methods in the component in response. This is essential for handling user interactions.

Example:

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

@Component({
  selector: 'app-event-binding',
  template: `<button (click)="onClick()">Click Me!</button>`
})
export class EventBindingComponent {
  onClick() {
    alert('Button clicked!');
  }
}

Use Case: Use event binding when you want to respond to user actions, such as clicks, key presses, or mouse movements.

4. Two-Way Binding

Why it's used: Two-way binding allows for a two-way synchronization between the component and the view. It is particularly useful in forms where user input needs to be reflected in the component's properties and vice versa.

Example:

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

@Component({
  selector: 'app-two-way-binding',
  template: `<input [(ngModel)]="name" placeholder="Enter your name">
             <p>Hello, {{ name }}!</p>`
})
export class TwoWayBindingComponent {
  name: string = '';
}

Use Case: Use two-way binding when you need to bind form inputs to component properties, allowing for real-time updates as the user types.

Angular Data Binding Example.

Below is a complete working example of an Angular application that demonstrates all four types of data binding: interpolation, property binding, event binding, and two-way binding.

Step 1: Set Up Angular Application

First, make sure you have Angular CLI installed. You can create a new Angular application using the following command:

ng new data-binding-example
cd data-binding-example

Step 2: Create a Component

Next, create a new component called data-binding:

ng generate component data-binding

Step 3: Update the Component

Now, open the data-binding.component.ts file and update it as follows:

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

@Component({
  selector: 'app-data-binding',
  templateUrl: './data-binding.component.html',
  styleUrls: ['./data-binding.component.css']
})
export class DataBindingComponent {
  title: string = 'Data Binding Example';
  imageUrl: string = 'https://via.placeholder.com/150';
  name: string = '';

  onClick() {
    alert(`Hello, ${this.name}!`);
  }
}

Step 4: Update the Template

Next, open the data-binding.component.html file and update it with the following code:

<h1>{{ title }}</h1> <!-- Interpolation -->

<img [src]="imageUrl" alt="Placeholder Image"> <!-- Property Binding -->

<button (click)="onClick()">Click Me!</button> <!-- Event Binding -->

<input [(ngModel)]="name" placeholder="Enter your name"> <!-- Two-Way Binding -->
<p>Hello, {{ name }}!</p> <!-- Interpolation -->

Step 5: Import FormsModule

To use two-way binding with ngModel, you need to import FormsModule. Open the app.module.ts file and update it as follows:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms'; // Import FormsModule
import { AppComponent } from './app.component';
import { DataBindingComponent } from './data-binding/data-binding.component';

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

Step 6: Update the Main Template

Finally, open the app.component.html file and include the data-binding component:

<app-data-binding></app-data-binding>

Step 7: Run the Application

Now, you can run the application using the following command: ng serve

Open your browser and navigate to http://localhost:4200. You should see the following:

A title displayed using interpolation.
An image is displayed using property binding.
A button that shows an alert with a greeting when clicked (event binding).
An input field that updates the greeting in real-time using two-way binding.

Summary

Interpolation: Displays component data in the template.
Property Binding: Binds component properties to HTML element properties.
Event Binding: Listens to events and executes component methods.
Two-Way Binding: Synchronizes data between the component and the view, especially in forms.

These data binding techniques enable developers to create dynamic and responsive applications in Angular, enhancing user experience and interaction.

Angular

Difference Between ngOnInit and constructor in Angular.

Probin Kumar Sah

July 16, 2025 No comments 0

In Angular, both the constructor and the ngOnInit lifecycle hook are used in components, but they serve different purposes and are called at different times in the component's lifecycle. Understanding the use and their difference will help you build a better Angular Application.

Constructor

The constructor is a TypeScript feature used to initialize class members. It is called when the component is instantiated. The constructor is called before Angular sets any input properties or runs any lifecycle hooks.

Usage: You typically use the constructor for dependency injection and to initialize class properties. However, you should avoid complex logic or operations that depend on the component's view or input properties.

ngOnInit

ngOnInit is a lifecycle hook provided by Angular that is called after the component's constructor and after Angular has initialized all data-bound properties. It is called once the component is fully initialized, and it is a good place to perform any additional initialization tasks that require access to input properties or the component's view.

Usage: You can use ngOnInit to fetch data from services, set up subscriptions, or perform any other initialization that requires the component to be fully set up.

Difference Between Constructor and ngOnInit.

Feature	`constructor()`	`ngOnInit()`
Purpose	Initializes class members and injects dependencies	Used for component initialization logic after inputs are set
Lifecycle	Runs when the class is instantiated (before Angular binds inputs)	Runs after the constructor, when Angular has fully initialized the component
Best Use	Dependency injection, initializing simple properties	Fetching data, calling APIs, and logic that depends on `@Input()`
Called By	JavaScript engine	Angular framework

Example Angular Code:

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

@Component({
  selector: 'app-example',
  templateUrl: './example.component.html',
})
export class ExampleComponent implements OnInit {
  data: string;

  constructor() {
    // Constructor logic (e.g., dependency injection)
    console.log('Constructor called');
  }

  ngOnInit() {
    // Initialization logic that requires the component to be fully set up
    this.data = 'Hello, World!';
    console.log('ngOnInit called');
  }
}

In this example, the constructor is used for basic setup, while ngOnInit is used to initialize the data property after the component is fully initialized.

Summary

Use a constructor for setting up dependencies and initializing properties.
Use ngOnInit for any logic that needs Angular to finish setting up the component (like input bindings or DOM access).

✅ Rule of Thumb: “Keep constructor light, move logic to ngOnInit().”

Mega Menu

TRENDING

How To Add Font Awesome in Angular?

Prerequisites

Method 1: Add Font Awesome Using CDN.

Method 2: Install Font Awesome via npm.

How To Check, Install and Update Angular on Your System.

Prerequisites: The Node.js and npm Foundation

Check Your Node.js and npm Versions

How to Check Your Angular CLI Version.

Check Global Angular CLI Version.

Check Project-Specific Angular Version

How To Install the Angular CLI.

How To Update Angular (CLI and Project).

Update Local Project Packages.

Conclusion.

How To Resolve Circular Dependency Error in Angular.

What is Dependency?

Dependency Example:

What is Circular Dependency?

Example of Circular Dependency in Angular.

Method 1: Resolve Circular Dependency Using Shared Service.

Method 2: Use forwardRef().

Types of Data Binding in Angular.

1. Interpolation

2. Property Binding

3. Event Binding

4. Two-Way Binding

Angular Data Binding Example.

Summary

Difference Between ngOnInit and constructor in Angular.

Constructor

ngOnInit

Difference Between Constructor and ngOnInit.

Summary

How To

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