What triggers Change Detection in Angular, and why is understanding this important?

Junior Angular Published: Nov 21, 2025

Quick Answer Change Detection triggers: any browser event (click, keyup), XHR response, timer (setTimeout, setInterval), Promise resolution. Zone.js patches all these to notify Angular. Avoid triggering CD unnecessarily: run non-UI work outside Angular zone (NgZone.runOutsideAngular), use OnPush strategy, use pure pipes, debounce frequent events. Understanding triggers is key to performance optimization.

Answer

Angular change detection is triggered by async events handled by Zone.js, such as timers, promises, user events, and HTTP calls.

Understanding these triggers helps avoid unnecessary re-renders, optimize performance, and decide when to use OnPush strategy.

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What triggers Change Detection in Angular, and why is understanding this important?

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