Mastering Change Detection cycle with a scroll example

> Author: Thomas Laforge ### Information This challenge will teach you how to avoid unnecessary change detection cycles. Zone.js will trigger a change detection cycle each time a scroll event is dispatched. However we only want to show or hide a button at a specific scroll position. Therefore, we only want to refresh our application once. > You can vizualise how many times CD is triggered by installing the [Angular chrome devTool](https://chrome.google.com/webstore/detail/angular-devtools/ienfalfjdbdpebioblfackkekamfmbnh) and starting a new recording on the profiler tab. ### Statement Your goal for this challenge is to avoid all those unnecessary change detection cycle and trigger a CD only when needed. #### Constraint: You cannot opt-out of zone.js. If this code is part of a large project and you opt out of zone.js, you will break many things within your application. ### Submitting your work 1. Fork the project 2. clone it 3. npm install 4. **nx serve scroll-cd** 5. _...work on it_ 6. Commit your work 7. Submit a PR with a title beginning with **Answer:12** that I will review and other dev can review. Mastering Change Detection cycle with a scroll example _You can ask any question on_ twitter