Pre Commit Hook for JSLint in Mercurial and Git

Question

I want to run JSLint before a commit into either a Mercurial or Git repo is done.

I want this as an automatic step that is set up instead of relying on the developer (mainly me) remembering to run JSLint before-hand. I normally run JSLint while developing, but want to specify a contract on JS files that they pass JSLint before being committed to the repo.

For Mercurial, this page spells out the precommit syntax, but the only variables that seem to be available are the parent1 and parent2 changeset IDs involved in the commit. What I really want are a list of file names that are involved with the commit, so that I can then choose the .js file and run jslint over them.

Similar issue for GIT, the default info available as part of the precommit script seems limited.

What might work is calling hg status/git status as part of the precommit script, parse that output to find JS files then do the work that way. I was hoping for something easier though, and I am not sure if calling status as part of a precommit hook reflect the correct information. For instance in Git if the changes files have not been added yet, but the git commit uses -a, would the files show up in the correct section of the git status output as being part of the commit set?

Update: I got something working, it is visible here: http://github.com/jrburke/dvcs_jslint/

Answer 1

The following is a variation of @Bitbieger's Git solution that works with Node.js and a local copy of node-jslint (i.e. you need to npm install jslint in your root repository directory).

Additionally the script:

• Runs jslint over all .html and .json files as well as .js
• Only runs jslint over files that have been added, copied or modified. This prevents jslint from erroring on files that have been renamed or deleted.
• Replicates any jslint errors for the user to see
• Uses the --indent 4 --white true jslint options to ensure source code consistency

To get it to work copy the following to .git/hooks/pre-commit and don't forget to chmod +x .git/hooks/pre-commit

# Pre-commit hook passing files through jslint
#
# This ensures that all js, html and json files are valid and conform
# to expectations.

ROOT_DIR=$(git rev-parse --show-toplevel)
JSLINT="${ROOT_DIR}/node_modules/.bin/jslint --indent 4 --white true"

for file in $(git diff-index --name-only --diff-filter=ACM --cached HEAD -- | grep -P '\.((js)|(html)|(json))$'); do
    if node $JSLINT $file 2>&1 | grep 'No errors found' ; then
        echo "jslint passed ${file}"
        exit 0
    else
        node $JSLINT $file
        exit 1
    fi  
done