Content Projection in Angular

In Angular, content projection is a powerful technique that allows developers to pass content from a parent component into a child component, and display it in a specific location within the child component's template. This mechanism enables component reusability and flexibility, making it an essential concept for building modular applications.

This blog post delves into the concept of content projection, its types, and provides an example to help you understand how to implement it effectively.

What is Content Projection?

Content projection allows you to project or "transclude" external content into a component’s template. It uses the <ng-content> directive, which acts as a placeholder in the child component’s template where the content provided by the parent component will be inserted.

Angular(DI) Resolution Modifiers

In Angular, one of its core strengths lies in its Dependency Injection (DI) system, which ensures that components and services can seamlessly interact. A key feature of this DI system is the use of Resolution Modifiers. In this blog post, we'll explore what Resolution Modifiers are, how they work, and their practical applications in Angular.

What Are Resolution Modifiers?

Resolution Modifiers in Angular provide specific instructions to the dependency injection system on how to resolve a dependency. They are used to modify the default behavior of Angular's DI system, allowing developers to handle more complex scenarios effectively.

Angular provides four main resolution modifiers:

1. @Optional
2. @Self
3. @SkipSelf
4. @Host

Angular Preloading Strategy : Enhancing User Experience and Performance

Angular offers several features to enhance performance and improve the user experience. One of these features is preloading, a mechanism to load modules in the background after the application has been bootstrapped.At the heart of this feature is the PreloadStrategy, a powerful tool for optimizing Angular applications.

In this blog post, we’ll explore what PreloadStrategy is, its significance, how it works, and how to customize it to suit your needs.

What is PreloadStrategy?

In Angular applications, lazy loading is commonly used to load modules only when needed, reducing the initial bundle size and improving load time. However, lazy loading might cause a delay when users navigate to a route whose module hasn’t been loaded yet. Preloading bridges this gap by loading lazy-loaded modules in the background after the application is initialized.

PreloadStrategy is an Angular interface that defines the strategy for preloading these modules. By default, Angular provides two built-in strategies:

1. NoPreloading: Disables preloading entirely.
2. PreloadAllModules: Preloads all lazy-loaded modules as soon as possible.

Understanding Resolvers in Angular

When building Angular applications, one of the common requirements is to fetch data before navigating to a route. For instance, consider a scenario where you want to display a user's details on a profile page. Instead of loading the route and showing a spinner while fetching data, wouldn't it be better to resolve the data before entering the route? This is where Angular Resolvers shine.

In this post, we'll explore what resolvers are, why they're essential, and how to use them effectively in your Angular applications

What is a Resolver in Angular?

A Resolver in Angular is a service that retrieves data before a route is activated. It ensures that your component is rendered with the required data already available, improving user experience by reducing the time spent waiting for asynchronous calls after the view is loaded.

Resolvers are part of Angular's Route Guards, which include CanActivate, CanDeactivate, CanLoad, and others. While these guards determine route activation, Resolvers focus specifically on fetching data.

Why Use Resolvers?

1. Optimized User Experience: By fetching data before rendering, you avoid rendering incomplete views with loading indicators.

Forms in Angular - A Comprehensive Guide to Building Reactive and Template-Driven Forms

Forms are a fundamental part of any web application, enabling users to interact with the app, provide information, and submit data. In Angular, forms can be implemented using two main approaches: Template-driven and Reactive forms. Each approach has unique benefits, so understanding how to use them effectively can elevate your Angular app development.

In this post, we'll dive into the following:

1. Template-driven forms
2. Reactive forms
3. Form validation
4. Comparing the two approaches

1. Template-Driven Forms

Template-driven forms in Angular rely heavily on Angular's two-way data binding. They’re built directly in the HTML template using directives like ngModel. Template-driven forms are ideal for simpler forms and are particularly helpful when you don’t need to programmatically control form behavior.

Angular Signals : A Practical Guide with Examples

Angular 17 recently introduced the concept of Signals to improve reactivity and simplify state management. Signals allow Angular applications to handle state changes in a more predictable, efficient, and declarative way. This blog will cover what Signals are, why they matter, and how to use them with practical examples.

What are Signals?

In Angular, a Signal is a reactive primitive that provides a new approach to managing and responding to state changes. With Signals, you can track changes to specific data points (variables or objects), allowing the app to automatically react when the data changes without needing complex change detection.

Why Use Signals?

Signals offer several benefits:

• Predictable reactivity: Signals enable precise control over when a component updates, leading to more predictable behavior.
• Improved performance: With Signals, Angular avoids unnecessary re-renders by updating only the affected parts.

Route Guards in Angular

When building Angular applications, managing access to different routes is crucial for both security and user experience. Angular provides a robust mechanism called Route Guards to control navigation. Let’s dive into what Route Guards are, the different types available, and how to implement them with examples.

What are Route Guards?

Route Guards are interfaces that allow you to control the navigation to and from routes in your Angular application. They help you decide whether a user can access a particular route or not. There are several types of Route Guards:

Lifecycle of an Angular service

Understanding the lifecycle of an Angular service is crucial for effectively managing dependencies and ensuring optimal performance in your application. Here’s a breakdown of the lifecycle of an Angular service:

1. Creation

When a service is first requested by a component, directive, or another service, Angular’s dependency injection system creates an instance of the service. This happens only once if the service is provided at the root level or a module level, ensuring a singleton instance.

Hierarchical Dependency Injection in Angular

Hierarchical Dependency Injection (DI) in Angular is a powerful feature that allows you to control the scope and lifetime of services. It enables you to create a hierarchy of injectors, where each injector can provide its own set of dependencies. This hierarchy mirrors the component tree, allowing for fine-grained control over which services are available to which parts of your application.

How Hierarchical Dependency Injection Works?

In Angular, every component has its own injector, and these injectors form a hierarchy. The root injector is created when the application starts, and child injectors are created for each component. When a component requests a dependency, Angular starts at the component’s injector and works its way up the hierarchy until it finds a provider for the requested dependency.

Difference between providedIn and providers array

providedIn

The providedIn property is used within the @Injectable decorator to specify where the service should be provided. This is a more modern and preferred way to provide services in Angular.

Global Scope: When you use providedIn: 'root', the service is registered with the root injector, making it a singleton and available throughout the entire application.

Understanding Providers in Angular

In Angular, providers are a fundamental concept that allows you to inject dependencies into your components, services, and other parts of your application. They play a crucial role in Angular's dependency injection (DI) system, making it easier to manage and share services across your application.

What is a Provider?

A provider is an instruction to the Angular dependency injection system on how to obtain a value for a dependency. When you configure a provider, you tell Angular how to create an instance of a service or value that can be injected into components, directives, pipes, or other services.

Understanding Lazy-Loaded Modules in Angular

Lazy loading is a design pattern in Angular that allows you to load modules only when they are needed, rather than loading all modules upfront. This can significantly improve the performance of your application by reducing the initial load time.

What is a Lazy-Loaded Module?

A lazy-loaded module is an Angular module that is loaded on demand. Instead of being included in the main bundle, it is loaded asynchronously when the user navigates to a route that requires the module.

Understanding Angular Dependency Injection

Dependency Injection (DI) is a design pattern used to implement IoC (Inversion of Control), allowing a class to receive its dependencies from an external source rather than creating them itself. Angular’s DI system is a powerful feature that makes it easy to manage dependencies and promote code reusability and testability.

How Dependency Injection Works in Angular?

In Angular, DI is used to provide components, services, and other classes with the dependencies they need. The Angular injector is responsible for creating and managing these dependencies. Here’s a step-by-step explanation of how DI works in Angular:

Understanding @Injectable and @Inject Decorators in Angular

In Angular, decorators are used to attach metadata to classes, methods, properties, and parameters. Two commonly used decorators are @Injectable and @Inject. While they might seem similar, they serve different purposes. Let’s dive into their differences and see how they are used with examples.

@Injectable Decorator

The @Injectable decorator is used to mark a class as available for dependency injection. It tells Angular's dependency injection system that the class can be injected as a dependency into other classes.

Standalone Components in Angular

A standalone component is a type of component that doesn’t belong to any specific Angular module.Before Angular version 14, when you created a component, you typically had to include it in the declaration array of a module; otherwise, Angular would throw an error during compilation.Standalone components are independent units that can be instantiated and used anywhere within an Angular application, regardless of the module structure. Standalone components can be useful for creating reusable UI elements or utility functions that are not specific to any module.

In this post, we'll explore standalone components in Angular and how to create them with a detailed example.

Creating a Standalone Component

First, make sure you're using Angular version 14. To create a component on its own, use the --standalone option with the command ng generate component.

ng g c component_name  --standalone

Decorators in Angular

There are several important concepts in Angular, and Decorators are an important concept to learn when you are working Angular. Decorators in Angular are a powerful and essential feature used to enhance and modify the behavior of classes, methods, and properties. Through this post we will learn about decorators, its types and how it is being used in real time applications.

What are Decorators?

Decorators are functions that are invoked with a prefixed @ symbol.Basically, a decorator provides configuration metadata that determines how the component, class or a function should be processed, instantiated and used at runtime.Decorators are applied to classes, class properties, and class methods using the following syntax:

@DecoratorName(arguments)

Angular comes with several built-in decorators, and you can also create custom decorators to extend or modify the behavior of your application.

Angular17 - Deferred Loading Using Defer Block

Angular 17 recently came out with several exciting updates.it has an exciting new feature called deferred loading

Lazy loading is a method that helps web apps load things like scripts only when necessary. Instead of loading everything at the start, it waits to load less important stuff until the user does something like interacting with the page or scrolling to a certain point.

Lazy loading improves the user experience by making the initial page load faster. This means users can begin using the app sooner while the less important parts load quietly in the background. It also decreases the amount of internet data needed and eases the strain on the server.

In earlier versions of Angular, we were able to load a specific part of the application later using the Router, or by using dynamic imports along with ngComponentOutlet.

Angular17 now has a @defer control block enabling lazy-loading of the content of the block. Lazy-loading also applies to the dependencies of the content of the block: all the components, directives and pipes will be lazy-loaded, too.

I will demonstrate the key aspects of lazy loading in Angular 17, such as

• Using @defer with a logical expression
• Using @defer with a declarative trigger condition

Angular 17 : New control flow syntax

Angular 17 recently came out with several exciting updates. One notable addition is the Control Flow feature. This new feature simplifies template writing by introducing a direct way to handle control flow within the template itself. Now, there's no need to rely on directives like *ngIf, *ngFor, and *ngSwitch for control flow as this new syntax streamlines the process.

This post will demonstrate a basic project using a new control flow method, moving away from the traditional directive-based approach. You can go through my other Angular post here.Let's begin right away!

Angular Project Setup

Before we start using the new feature, let's make sure you have an Angular project set up and ready to go. If you haven't done so yet, create a new Angular project using these commands with the Angular CLI:

npm install -g @angular/cli@latest
ng new ng17-control-flows

This command creates a fresh Angular project, including all the essential files and dependencies with the latest version.

Once it's set up, open the app.component.html file and remove the default Angular code. Let's add a basic HTML structure to it instead.

<h1>NG -17 :New Control Flows</h1>

Conditionally rendered control blocks: @if and @else

Let’s start with the replacement of *ngIf.

In the first example, I create a checkbox and bind it to the isChecked property.Starting with a default value of true, the checkbox appears checked, displaying the content within the @if block.The examples below are from the app.component.html template file:

Angular - Understanding ReplaySubject in Angular

In this article, we'll delve into the core concepts of ReplaySubject and how it can enhance your Angular applications by granting access to historical data. Regardless of your expertise level, this guide will help you effectively harness the capabilities of ReplaySubject.

Understanding ReplaySubject

At its core, a ReplaySubject is a specialized type of Subject in the RxJS library. Like all Subjects, it serves as both an Observable and an Observer. What sets ReplaySubject apart is its unique ability to buffer a specific number of values and replay them to future subscribers. Think of it as a time-travel device that captures past emissions and shares them with new subscribers.

Key Features and Benefits

1.Time-Travel for Subscribers: Imagine welcoming latecomers to a party who wish to experience the excitement from the beginning. ReplaySubject allows subscribers to access historical data, even if they arrive after the data was emitted.
2.Customizable Buffer Size: ReplaySubject empowers you to determine how many values to store in its buffer. By setting the buffer size during creation, you have control over the amount of historical data you retain.
3.No Initial Value Required: Unlike BehaviorSubject, which mandates an initial value, ReplaySubject doesn't demand this, making it perfect for scenarios where an initial value isn't available.
4.Efficient Caching Mechanism: ReplaySubject can act as an intelligent caching mechanism, ensuring that expensive data requests are made only once. Subsequent subscribers receive cached data instead of triggering new requests.

Understanding Data Sharing Between Angular Components using BehaviorSubject

In the realm of complex Angular applications, one of the prevalent challenges that developers encounter is the efficient sharing of data among distinct components. Angular offers a potent tool to address this predicament: the 'BehaviorSubject'. This article delves into the practical utilization of 'BehaviorSubject' to facilitate data sharing across components within an Angular application.

What is BehaviorSubject?

In straightforward terms, a 'BehaviorSubject' is a variant of RxJS subject that retains a current value and transmits it to newly subscribing entities. It resembles a conventional 'Subject', but with a pivotal distinction – it constantly holds a value, even when no subscribers are present. When fresh components subscribe to the 'BehaviorSubject', they promptly receive the prevailing value. This characteristic renders it an optimal solution for data sharing that necessitates accessibility and updates across diverse parts of an application.

Establishing the BehaviorSubject

The initial step involves creating an Angular service called 'SharedDataService' to accommodate the shared data and the 'BehaviorSubject'.

// shared-data.service.ts
import { Injectable } from '@angular/core';
import { BehaviorSubject } from 'rxjs';

@Injectable({
  providedIn: 'root',
})
export class SharedDataService {
  private dataSubject: BehaviorSubject<string> = new BehaviorSubject<string>('Initial Value');

  public data$ = this.dataSubject.asObservable();

  public updateData(newValue: string): void {
    this.dataSubject.next(newValue);
  }
}