Component Communication, Lifecycle Hooks, Change Detection, and Performance Basics
Understand how Angular components share data, react to lifecycle moments, and update the screen efficiently.
Inside this chapter
- Parent-Child Communication
- Lifecycle Hooks
- Change Detection
- Performance-Oriented Habits
- Real Example
Series navigation
Study the chapters in order for the clearest path from Angular fundamentals to advanced architecture, testing, performance, and deployment. Use the navigation at the bottom to move smoothly across the full tutorial series.
Parent-Child Communication
Components often communicate through inputs and outputs. Parents pass data downward, while children emit events upward when user actions or internal state changes should be reported.
@Input() course!: Course;
@Output() selected = new EventEmitter<number>();Lifecycle Hooks
ngOnInitfor initialization workngOnChangeswhen input values changengOnDestroyfor cleanup
Students should use lifecycle hooks deliberately rather than placing all logic in constructors or scattering setup randomly.
Change Detection
Angular updates the view when data changes. Understanding change detection helps teams avoid unnecessary rerendering, expensive computations in templates, and surprising UI behavior. This topic becomes especially important in large dashboards and data-heavy screens.
Performance-Oriented Habits
Use track-by strategies for repeated lists, keep templates clean, avoid repeated heavy method calls from markup, and unsubscribe where appropriate. Strong performance usually comes from many good habits, not one magic trick.
Real Example
A catalog page with hundreds of items, filters, and sorting controls can become slow if every keystroke or interaction triggers too much recomputation. Communication patterns and change detection discipline directly influence perceived speed.