1. Introduction

This tutorial aims to guide you on how to implement Route Guards and Lazy Loading in Angular. These advanced concepts can help optimize your applications by improving performance and security. By the end of this tutorial, you will be able to:

• Understand the concept of Route Guards and Lazy Loading.
• Implement Route Guards to protect routes in your application.
• Implement Lazy Loading to enhance your application's performance.

Prerequisites: Basic knowledge of Angular and Angular routing is required.

2. Step-by-Step Guide

Route Guards

Route guards in Angular are interfaces which can tell the router to allow or deny access to certain routes.

• CanActivate: Checks if a route can be activated.
• CanActivateChild: Checks if child routes of a route can be activated.
• CanDeactivate: Checks if the current route can be deactivated.
• Resolve: Performs route data retrieval before route activation.
• CanLoad: Checks if a module can be loaded lazily.

Lazy Loading

Lazy Loading is a design pattern in Angular which allows you to load Angular modules only when they are needed, rather than loading all at once at startup. This reduces the initial load time and memory usage of your application.

3. Code Examples

Implementing Route Guard

Let's create a simple route guard using CanActivate:

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

@Injectable({
  providedIn: 'root'
})
export class AuthGuard implements CanActivate {
  canActivate(
    next: ActivatedRouteSnapshot,
    state: RouterStateSnapshot): boolean {
    // Here you can implement your logic to allow or deny access to certain routes
    // For example, we are allowing access to all routes
    return true;
  }
}

In the above code, we have created a service AuthGuard which implements the CanActivate interface. The canActivate method will decide whether a route can be activated or not.

Implementing Lazy Loading

For implementing Lazy Loading, first create a module:

ng generate module products

Then in your app-routing.module.ts, you can define your lazy-loaded route like this:

const routes: Routes = [
  { path: 'products', loadChildren: () => import('./products/products.module').then(m => m.ProductsModule) }
];

Here, ProductsModule will only be loaded when the user navigates to '/products'.

4. Summary

In this tutorial, we learned about Route Guards and Lazy Loading in Angular. We saw how to implement a basic Route Guard using the CanActivate interface and how to implement Lazy Loading for a module. Next, you could look into other Route Guard interfaces and more complex Lazy Loading scenarios.

5. Practice Exercises

1. Create a Route Guard that only allows access to a route if a certain condition is met.
2. Implement Lazy Loading for two of your existing modules.
3. Create a Route Guard that resolves some data before activating a route.

Remember, practice is key to understanding and mastering these concepts. Happy Coding!