Pre-commit hook for ESLinting that works with sourcetree

pre-commit

# !/bin/sh
#
# An example hook script to verify what is about to be committed.
# Called by "git commit" with no arguments.  The hook should
# exit with non-zero status after issuing an appropriate message if
# it wants to stop the commit.
#
# To enable this hook, rename this file to "pre-commit".

HAS_NODE=`which node 2> /dev/null || which nodejs 2> /dev/null || which iojs 2> /dev/null`

#
# There are some issues with Source Tree because paths are not set correctly for
# the given environment. Sourcing the bash_profile seems to resolve this for bash users,
# sourcing the zshrc for zshell users.
#
# https://answers.atlassian.com/questions/140339/sourcetree-hook-failing-because-paths-don-t-seem-to-be-set-correctly
#
function source_home_file {
  file="$HOME/$1"
  [[ -f "${file}" ]] && source "${file}"
}
source_home_file ".bash_profile" || source_home_file ".zshrc" || true

#
# Determine node.js binary name and location
#
NODE=`which node 2> /dev/null`
NODEJS=`which nodejs 2> /dev/null`
IOJS=`which iojs 2> /dev/null`
LOCAL="/usr/local/bin/node"
BINARY=

#
# Figure out which binary we need to use for our script execution.
#
if [[ -n "$NODE" ]]; then
  NODE_BINARY="$NODE"
elif [[ -n "$NODEJS" ]]; then
  NODE_BINARY="$NODEJS"
elif [[ -n "$IOJS" ]]; then
  NODE_BINARY="$IOJS"
elif [[ -x "$LOCAL" ]]; then
  NODE_BINARY="$LOCAL"
fi

if git rev-parse --verify HEAD >/dev/null 2>&1
then
    against=HEAD
else
    # Initial commit: diff against an empty tree object
    against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

eslint=$(PATH="./node_modules/.bin:$PATH" which eslint)
if [[ -e "$eslint" ]]
then
    jsfiles=$(git diff-index --cached --name-only --diff-filter=ACM $against | grep '.js$')
    if [[ -n "$jsfiles" ]]
    then
        eslintOutput=$($NODE_BINARY node_modules/eslint/bin/eslint.js -f stylish -o .eslint.log $jsfiles)
        if [[ $? != 0 ]]
        then
            cat .eslint.log
            exit 1
        fi
    fi
fi