Generally speaking, when we introduce a package, we just import Pack from 'pack';
But I saw a lot of packages, there are different versions in the folder, and there are more than one file that needs to be used. It is js, or it may require a css file. In this case, which file should be declared in it?
Or directly:
import Pack from 'pack/dist/...';
There is a main attribute in package.json that points to the root, usually index.js or the like.