NodeJS has a really great amount of 3rd party libraries. Anything you can imagine, you can find it in NPM. But the grammar of JavaScript sucks, which make it really hard to maintain a large scale NodeJS application.
ASP.NET Core mainly use C# or F# as development language, much better then JavaScript. But as I began to use ASP.NET Core from years ago, it leaks of 3rd party packages and quality is not good, but I believe more and more packages will come and quality will become great.
So, if you are writing simple scripts, use NodeJS. Making large application? choose ASP.NET Core
https://blogs.msdn.microsoft.com/dotnet/2018/08/20/bing-com-runs-on-net-core-2-1/
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