mjs.sh

# rename all .js to .mjs
for f in **/*.js; do mv -- "$f" "${f%.js}.mjs"; done

# add .mjs to all file-based import statements*
find . -type f -name "*.mjs" -exec sed -i '' -E "s/(import.+'\.[a-zA-Z0-9\.\/-]+)';/\1\.mjs';/g" {} \;

# *NOTES: 
# 1. This will double up existing .mjs extension in imports.
# Couldn't get phrase negation working in this sed substitution regex :(
#
# 2. Doesn't work on multi-line import statements