UPDATE: Looks like latest update of VS 2017 (15.3) solve the issue.
This is because of the new javascript language service
http://aka.ms/JavaScriptExperimental
To disable and bring back JS, go to: Tools - Options - text editor - Javascript/Typescript - Language service - General and disable the very first option.
![[愿得一人]](https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000012.jpg)