Shell script to lint only changed files to be used as a githook (specific to my project)

eslint-changed.sh

#!/usr/bin/env bash
set -e

# allow being run from somewhere other than the git rootdir
gitroot=$(git rev-parse --show-cdup)

# default gitroot to . if we're already at the rootdir
gitroot=${gitroot:-.};

nm_bin=$gitroot/node_modules/.bin

echo "Linting changed files"
SRC_FILES=$(git diff --staged --diff-filter=ACMTUXB --name-only -- '*.js' | grep -v '\.test\|mock\|e2e\.js$') && x=1
TEST_FILES=$(git diff --staged --diff-filter=ACMTUXB --name-only -- '*.js' | grep '\.test\|mock\|e2e\.js$') && x=1

function lint() {
  if [ "$2" ]; then
    echo "Linting changed $1 files"
    $nm_bin/eslint $2 -c other/${1}.eslintrc
  else
    echo "No $1 files changed"
  fi
}

lint "app" $SRC_FILES;
lint "test" $TEST_FILES;

echo "⚡️  changed files passed linting! ⚡️"

See also: https://pypi.org/project/lint_diffs: works with many linters (including eslint) and many vcs. It can run on all changed files, and show linter errors for the whole file, or for only changed lines. Good for gradually improving linter errors.