midAngular
What is Angular TrackBy in ngFor?
Updated Apr 28, 2026
Short answer
TrackBy optimizes rendering by identifying list items uniquely.
Deep explanation
Without TrackBy, Angular re-renders entire list. TrackBy improves performance by updating only changed items.
Real-world example
Efficient rendering of large lists.
Common mistakes
- Not using TrackBy in big lists.
Follow-up questions
- Why TrackBy?
- What happens without it?