How to solve in macOS High Sierra xcrun: error: invalid active developer path /Library/Developer/CommandLineTools

I was just trying in my friend computer downgrade her npm version from 9.5.0 to 8.11.3, and suddenly I had to face an error:

(xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools))

I didn't know that she hadn't installed Xcode CommandLine, so, this is the way to do that:

xcode-select --install

So, that's all. Good luck.