nuget package inside
How do I know how jQuery (or similar nuget package) nuget package being constructed? Especially I would like to know how these *.js being copied/ installed to specific folder (scripts) of a ASP.net MVC project
You can simply open a .nupkg file with any zip-utility (e.g. 7zip) and extract the archive to see its contents.
A NuGet package can have 3 folders: lib, content & tools. Anything in the content folder will be injected into the target project using the same relative path to the project root as to the content folder of the nuget package.
More info here: http://docs.nuget.org/docs/creating-packages/package-conventions
The list of public jQuery/jQuery plugins that have been "NuGetified" can be see here http://nuget.org/packages?q=jquery The jQuery NuGet package page http://nuget.org/packages/jQuery has a note saying that it is maintained by the NuGet Community Packages project.