Lazy Loading — Complete Guide
Lazy Loading — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of MEAN Stack Tutorial on Toolliyo Academy.
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MEAN Stack Tutorial · Lesson 72 of 100
Lazy Loading
Stack ✓ → Projects
Projects · 2 — Apps · ~10 min · MEAN — Performance & Testing
What is this?
Lazy loading downloads Angular feature code only when user navigates to that route — shrinking initial MeanVerse bundle.
Why should you care?
ERP modules unused by most users should not block first paint.
See it live — copy this example
Paste into your MeanVerse project (Angular + Express + MongoDB), then run with ng serve / node / mongosh as noted.
export const routes: Routes = [
{
path: 'banking',
loadChildren: () => import('./features/banking/banking.routes').then(m => m.BANKING_ROUTES)
},
{
path: 'healthcare',
loadComponent: () => import('./features/healthcare/patient-portal.component')
.then(m => m.PatientPortalComponent)
}
];
// banking.routes.ts exports BANKING_ROUTES with child paths
What happened?
- loadChildren pulls separate JS chunk on first /banking visit.
- loadComponent lazy-loads single standalone component.
- Users who never open healthcare never download it.
Practice next
- Split MeanVerse by domain feature routes.
- Verify separate chunks in dist/ after build.
- Preload strategy optional for likely next routes.
- Add withPreloading(PreloadAllModules) for admin users.
- Measure LCP before and after lazy split.
Remember
Lazy routes defer JS download. loadComponent for standalone features. Critical path stays in main bundle.
Multi-product shell
MeanVerse users enable only SaaS module; banking chunk never loads.
Outcome: Initial bundle drops 40%; login faster on mobile.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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