If like me and want to have a comprehensive understanding of the change detection mechanism in Angular you’ll have to explore the sources since there is not much information available on the web. Most articles mention that each component has its own change detector which is responsible for checking the component, but they don’t go beyond that and mostly focus on use cases for immutables and change detection strategy. This article provides you with the information required to understand why use cases with immutables work and how change detection strategy affects the check. Also, what you will learn from this article will enable you to come up with various scenarios for performance optimization on your own.

This article consists of two parts. The first part is pretty technical and contains a lot of links to the sources. It explains in detail how the change detection mechanism works under the hood. Its content is based on the newest Angular version — 4.0.1. The way how change detection mechanism is implemented under the hood in this version is different from the earlier 2.4.1. If interested you can read a little about how it worked in this stackoverflow answer.

The second part shows how change detection can be used in the application and its content is applicable for both earlier 2.4.1 and the newest 4.0.1 versions of Angular since public API has not changed.

#angular #change-detection