The VIP pre-commit hook runs JS through YUI Compressor to do syntax checking. We need to do the same for the pre-commit hook and the .travis.yml, something like:

wget https://github.com/yui/yuicompressor/releases/download/v2.4.8/yuicompressor-2.4.8.jar
for js in $(find . -name '*.js'); do
    java -jar yuicompressor-2.4.8.jar -o /dev/null $js 2>&1
    if [ $? != 0 ]; then
        exit 1;
    fi
done

• Check syntax with YUI Compressor
• Check with VIP which other commands are included in the SVN pre-commit hook (see https://github.com/Automattic/vip-quickstart/issues/204)