OnChange life cycle event

The OnChanges life cycle event is triggered whenever the component's input(s) change. In the case of VideoPlayerComponent, it is the videos array input property that changes whenever a new exercise is loaded. We use this life cycle event to recreate the safeVideoUrls array and re-bind it to the view. Simple!

Video panel implementation is now complete. Let's add a few more minor enhancements and explore it a bit more in Angular.