midAngularJS
What are watchers in AngularJS?
Updated Apr 28, 2026
Short answer
Watchers observe model changes and trigger updates during digest cycle.
Deep explanation
Each binding creates a watcher. AngularJS tracks expressions and executes associated functions when values change.
Real-world example
Tracking form input changes dynamically.
Common mistakes
- Too many watchers degrading performance.
Follow-up questions
- What is $watchCollection?
- Why watchers expensive?