ESLint 3.0 Git Pre Commit Hook

pre-commit

#!/bin/sh

# Get a list of all JS files currently staged for commit
files=$(git diff --cached --name-only | grep '\.jsx\?$')

# Prevent ESLint help message if no files matched
if [ -z "$files" ] ; then
  echo "(No JavaScript files to lint.)"
  exit 0
fi

failed=0
for file in ${files}; do
  if [ -f "$file" ]; then
    # --stdin makes eslint read from the output of `git show :<file>`, while
    # --stdin-filename <file> makes eslint treat that input as if it actually
    # is the contents of <file>
    if ! git show :"$file" | eslint --stdin --stdin-filename "$file"
    then
      failed=1
    fi
  fi
done

if [ $failed -ne 0 ] ; then
  echo "ESLint failed, git commit denied!"
  exit 1
fi

This is an improved version of @wesbos' original here. This improvement specifically lints the staged versions of the JS files that are being committed. This version also runs on the standard /bin/sh and is more POSIX-compliant (the ShellCheck tool helped with checking that).