javascript syntax check for a git pre-commit

pre-commit.sh

#!/bin/sh

for js in $(git diff-index --name-only HEAD); do
  echo Checking $js
  if ( [ -f $js ] ); then 
    if jsl --process $js > /dev/null ; then
        echo $js
    else
        echo "js files failed $js"
        jsl -nologo -nofilelisting -nosummary --process $js
        exit 1
    fi  
  fi
done