Put this in .git/hooks/pre-commit then run chmod a+x .git/hooks/pre-commit

pre-commit

#!/bin/bash

# Pre commit hook that prevents FORBIDDEN code from being commited.
# Add unwanted code to the FORBIDDEN array as necessary

FILES_PATTERN='\.(rb|js|coffee)(\..+)?$'
FORBIDDEN=( debugger ruby-debug )

for i in "${FORBIDDEN[@]}"
do
  git diff --cached --name-only| grep ".js" |xargs sed 's/ //g'|grep "ha_mobile.debug=true" && \
        echo 'COMMIT REJECTED Found ha_mobile.debug=true references. Please remove them before commiting' && exit 1

  git diff --cached --name-only | \
        grep -E $FILES_PATTERN | \
        GREP_COLOR='4;5;37;41' xargs grep --color --with-filename -n $i && \
        echo 'COMMIT REJECTED Found'  $i 'references. Please remove them before commiting' && exit 1
done

exit 0