Exact match file extension filter using grep

Question

I am working on running cat on all files with JS/JSX/SCALA extensions, I've tried the following

git ls-files | grep ".[js|jsx|scala]$"
git ls-files | grep ".*js|jsx|scala"

The end result will eventually look like this

git ls-files | grep -e ".*[js|jsx|scala]$" | xargs cat | wc -l

But I keep getting more files like yaml, yml

Answer 1

Use a group:

git ls-files | grep -E '\.(js|jsx|scala)$'

The \.(js|jsx|scala)$ pattern matches a dot and then js , jsx or scala and then the end of string.

Mind the -E option enabling POSIX ERE compliance.