Angular CLI creates vendor.js and I don't know Why and What is the use of it?? Size of this file is about 3.2MB for a new app!!
Does this file contains Angular 6 Javascript Source?
Don't you think this is big file for loading on internet on low speed connections?
This file includes all libraries that you added into your project. If you build your app on production mode the file size will be smaller.
ng build --prod