post-checkout

#!/bin/bash
#
# Check package.json and npm install after git checkout.
# Put this to .git/hooks/post-checkout
#

PREVIOUS_HEAD=$1
NEW_HEAD=$2
BRANCH_SWITCH=$3

if [ $(git diff $PREVIOUS_HEAD..$NEW_HEAD --name-only -- package.json | wc -l) == "1" ]; then
    echo "[post-checkout] package.json changed"
    npm install
fi

running npm prune should be useful too