How does lazy loading improve performance?

By reducing the size of the initial bundle, lazy loading ensures faster application load times and better user experience, especially for large apps.

What is Lazy Loading in Angular | FullStackPrep.Dev

Q: What is lazy loading in Angular?

Lazy loading in Angular refers to loading feature modules only when they are needed, rather than during the initial application load.

💡 Concept Name

Lazy Loading – A performance optimization technique in Angular that loads feature modules only when they are needed instead of during the initial application load.

📘 Quick Intro

Lazy loading splits the Angular app into multiple bundles. These bundles are loaded on demand when the user navigates to a specific route, reducing the initial bundle size and improving loading speed.

🧠 Analogy / Short Story

Imagine a book with many chapters, but you only read the chapters you’re interested in. Angular lazy loading only “opens” (loads) modules when you choose to “read” (navigate to) them.

🔧 Technical Explanation

📦 Feature Modules: Are split into separate files using the Angular router.
🧠 Route-based Loading: Routes are configured with loadChildren to load modules dynamically.
🚀 Improved Performance: Faster initial load time, especially in large applications.
🎯 Angular CLI Support: Automatically handles code-splitting and module bundling.
🔁 CanCombine With Guards: Often used with CanLoad to prevent unauthorized module loading.

🎯 Purpose & Use Case

✅ Used for large apps with many features or sections.
✅ Optimizes mobile performance by avoiding unnecessary bundle downloads.
✅ Keeps core bundle size small, improving time to interactive.

💻 Real Code Example

// app-routing.module.ts
const routes: Routes = [
  {
    path: 'admin',
    loadChildren: () => import('./admin/admin.module').then(m => m.AdminModule)
  }
];

❓ Interview Q&A

Q1: What is lazy loading in Angular?
A: A technique that loads modules only when they are required, reducing initial load time.

Q2: Which Angular feature enables lazy loading?
A: The loadChildren property in the routing configuration.

Q3: What are the benefits of lazy loading?
A: Faster initial load, better performance, and efficient resource usage.

Q4: What happens if a user never visits a lazy-loaded route?
A: That module is never downloaded, saving bandwidth.

Q5: Can guards be used with lazy loading?
A: Yes, especially CanLoad to restrict access before loading.

📝 MCQs

Q1. What is lazy loading?

Loading all modules upfront
Delaying service calls
Loading modules on demand
Preloading assets

Q2. Which Angular property enables lazy loading?

path
component
loadChildren
redirectTo

Q3. Why use lazy loading?

Reduce file size
Improve performance
Add animations
Enable forms

Q4. When does Angular load a lazy module?

During app start
After login
On user interaction
When its route is visited

Q5. What happens if a lazy route is never visited?

It fails
It is preloaded
It is never loaded
It slows app

Q6. Which guard is best with lazy modules?

CanActivate
CanDeactivate
CanLoad
CanChild

Q7. Can you lazy load multiple modules?

No
Only one
Yes
Only root module

Q8. Which file defines lazy-loaded routes?

Main.ts
AppComponent
Routing module
Environment.ts

Q9. Is lazy loading helpful for mobile apps?

No
Yes
Only for desktop
Rarely

Q10. What does lazy loading reduce?

App logic
Routing complexity
Initial bundle size
Code quality

💡 Bonus Insight

You can combine lazy loading with Angular preloading strategies to preload certain modules in the background after the app loads. This provides both speed and seamless user experience.

📄 PDF Download

Need a handy summary for your notes? Download this topic as a PDF!

📄 PDF Download Coming Soon

What is Lazy Loading in Angular