Setup Instructions: On-Demand Preloading in Angular

1. Custom Preloading Strategy: Implement a class that extends PreloadingStrategy. In the preload method, check for a custom route data property (e.g., preloadOnDemand) and return an observable that triggers when your service requests preloading.
2. Preloading Service: Create a service with a method (e.g., triggerPreload(path: string)) that signals your strategy to preload a specific route/module. Use RxJS Subject or BehaviorSubject for communication.
3. Router Configuration: In your router setup, provide your custom preloading strategy using withPreloading(CustomPreloadingStrategy) and set data: { preloadOnDemand: true } on routes you want to support on-demand loading.
4. Component Integration: Inject your preloading service in the relevant component (e.g., user list). Call the service’s method on a user action (like mouseenter on a link) to trigger preloading for the target route.
5. Testing: Use browser DevTools to monitor network requests. Verify that the module is only loaded when you trigger the event (hover/click), not on initial navigation.
6. Best Practices: Only preload modules that are likely to be needed soon. Avoid preloading everything to preserve bandwidth and performance.