Why routing is needed for SPAs in Angular - See It in Action

Why routing is needed for SPAs

📖 Scenario: You are building a simple single-page application (SPA) for a small online store. The app has different sections like Home, Products, and Contact Us. You want users to navigate between these sections without the page reloading.

🎯 Goal: Build a basic Angular SPA with routing that lets users switch between Home, Products, and Contact Us pages smoothly.

📋 What You'll Learn

Create a basic Angular app structure with three components: HomeComponent, ProductsComponent, and ContactComponent

Set up Angular routing to navigate between these components

Use routerLink in the navigation menu for user-friendly links

Display the correct component content when the user clicks a link without reloading the page

💡 Why This Matters

🌍 Real World

Most modern web apps use SPAs to provide fast, smooth user experiences by loading content dynamically without full page reloads.

💼 Career

Understanding routing is essential for frontend developers working with Angular or other SPA frameworks to build user-friendly navigation.

1

Create the initial components

Create three Angular components named HomeComponent, ProductsComponent, and ContactComponent with simple template text inside each.

Angular

// Create HomeComponent, ProductsComponent, and ContactComponent with basic template text
// Your code here

Hint

Use @Component decorator to create each component with a simple template.

2

Set up the routing configuration

Create a routing configuration array called routes that maps the path '' to HomeComponent, 'products' to ProductsComponent, and 'contact' to ContactComponent.

Angular

import { Routes } from '@angular/router';

// Define routes array mapping paths to components
// Your code here

Hint

Use an array of objects with path and component properties for routing.

3

Add router outlet and navigation links

In the main app component template, add a navigation menu with routerLink directives for Home, Products, and Contact. Also add a <router-outlet> tag to display routed components.

Angular

Hint

Use <a routerLink="path"> for navigation and <router-outlet> to show routed content.

4

Import RouterModule and apply routing

In the main app module, import RouterModule from @angular/router and call RouterModule.forRoot(routes) inside the imports array of @NgModule.

Angular

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { RouterModule } from '@angular/router';

// Add RouterModule.forRoot(routes) to imports array
@NgModule({
  declarations: [AppComponent, HomeComponent, ProductsComponent, ContactComponent],
  imports: [BrowserModule, /* Your code here */],
  bootstrap: [AppComponent]
})
export class AppModule {}

Hint

Import RouterModule and add RouterModule.forRoot(routes) to the imports array in @NgModule.

Practice

1. Why do Single Page Applications (SPAs) like Angular apps need routing?

easy

A. To disable navigation between different parts of the app

B. To change views without reloading the whole page

C. To make the app slower by adding extra steps

D. To reload the entire website every time a link is clicked

Solution

1. Step 1: Understand SPA behavior

   SPAs load a single HTML page and dynamically update content without full reloads.

2. Step 2: Role of routing in SPAs

   Routing allows changing views or components based on URL without reloading the entire page, making navigation smooth.

3. Final Answer:

   To change views without reloading the whole page -> Option B

4. Quick Check:

   Routing enables smooth view changes = D [OK]

Hint: Routing lets SPAs switch views without full page reloads [OK]

Common Mistakes:

• Thinking SPAs reload the whole page on navigation
• Believing routing slows down the app
• Confusing routing with disabling navigation

2. Which of the following is the correct way to define a route in Angular?

easy

A. { link: 'home', page: HomeComponent }

B. { url: 'home', view: HomeComponent }

C. { route: 'home', element: HomeComponent }

D. { path: 'home', component: HomeComponent }

Solution

1. Step 1: Recall Angular route syntax

   Angular routes use objects with path and component keys.

2. Step 2: Match correct keys

   Only { path: 'home', component: HomeComponent } uses path and component correctly.

3. Final Answer:

   { path: 'home', component: HomeComponent } -> Option D

4. Quick Check:

   Angular routes use path and component keys = A [OK]

Hint: Angular routes use 'path' and 'component' keys [OK]

Common Mistakes:

• Using wrong keys like url or route instead of path
• Confusing component with element or view
• Mixing route object structure with HTML attributes

3. Given this Angular route configuration:

const routes = [
  { path: '', component: HomeComponent },
  { path: 'about', component: AboutComponent }
];

What component will display when the URL is /about?

medium

A. HomeComponent

B. No component, shows blank page

C. AboutComponent

D. Error page component

Solution

1. Step 1: Match URL to route path

   The URL /about matches the route with path: 'about'.

2. Step 2: Identify component for matched route

   The route with path: 'about' uses AboutComponent.

3. Final Answer:

   AboutComponent -> Option C

4. Quick Check:

   URL '/about' loads AboutComponent = C [OK]

Hint: URL path matches route path to load component [OK]

Common Mistakes:

• Assuming empty path matches '/about'
• Thinking HomeComponent loads for all URLs
• Expecting error or blank page without reason

4. What is wrong with this Angular routing code?

const routes = [
  { path: 'home', component: HomeComponent },
  { path: 'about', component: AboutComponent }
];

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

The app does not navigate to the About page when clicking the link <a routerLink='/about'>About</a>.

medium

A. RouterModule is not imported in the main app module

B. The routes array is missing a default route for '' path

C. routerLink should be written as routerlink (lowercase L)

D. The component names are incorrect

Solution

1. Step 1: Check routing module setup

   The routing module is defined correctly but must be imported in the main app module to work.

2. Step 2: Identify missing import

   If AppRoutingModule is not imported in AppModule, routing won't activate, causing navigation failure.

3. Final Answer:

   RouterModule is not imported in the main app module -> Option A

4. Quick Check:

   Routing module must be imported in app module = B [OK]

Hint: Always import routing module in main app module [OK]

Common Mistakes:

• Thinking routerLink attribute is case-sensitive
• Assuming default route is required for all navigation
• Blaming component names without error evidence

5. You want your Angular SPA to show a 'Not Found' page when users enter an unknown URL. How should you add this behavior using routing?

hard

A. Add a route with path: '**' and a NotFoundComponent

B. Add a route with path: '' and a NotFoundComponent

C. Add a route with path: '404' and redirect all unknown URLs manually

D. No routing needed; Angular shows a default error page automatically

Solution

1. Step 1: Understand wildcard route usage

   Angular uses path: '**' as a wildcard to catch all unmatched URLs.

2. Step 2: Assign NotFoundComponent to wildcard route

   Defining { path: '**', component: NotFoundComponent } shows the Not Found page for unknown URLs.

3. Final Answer:

   Add a route with path: '**' and a NotFoundComponent -> Option A

4. Quick Check:

   Wildcard '**' route handles unknown URLs = A [OK]

Hint: Use '**' path to catch unknown URLs for Not Found page [OK]

Common Mistakes:

• Using empty path '' for Not Found page
• Manually redirecting unknown URLs instead of wildcard
• Expecting Angular to handle unknown URLs without setup