Javascript linting precommit hook with jscs and jshint

js-pre-commit-hook.sh

#!/bin/bash
#
# A hook to disallow js lint errors to be committed
#
# This is a pre-commit hook.
#
# To install this you can either copy or symlink it to
# $GIT_DIR/hooks/pre-commit
#
# Set up with npm install --save-dev jshint jscs
# OR
# Globally with npm install -g jshint jscs
#
# Author: Wei Kin Huang

# necessary check for initial commit
if git rev-parse --verify HEAD >/dev/null 2>&1; then
    AGAINST_REV=HEAD
else
    # Initial commit: diff against an empty tree object
    AGAINST_REV=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

NODE_BIN="$(which node 2>/dev/null)"
if type cygpath >/dev/null 2>&1; then
    NODE_BIN="$(cygpath -u "c:/Program Files/nodejs/node.exe")"
fi

if ! type "$NODE_BIN" >/dev/null 2>&1; then
    echo "JS Syntax check failed:"
    echo "NodeJs binary does not exist or is not in path: node"
    echo "You can bypass this hook with the --no-verify (-n) option"
    exit 1
fi

NODE_CMD_SUFFIX=""
if [[ "$(uname)" = MINGW* ]]; then
    NODE_CMD_SUFFIX=".cmd"
fi
JSCS_BIN=""
if type jscs >/dev/null 2>&1; then
    JSCS_BIN=jscs
elif [[ -e "./node_modules/.bin/jscs${NODE_CMD_SUFFIX}" ]]; then
    JSCS_BIN="./node_modules/.bin/jscs${NODE_CMD_SUFFIX}"
fi
JSHINT_BIN=""
if type jshint >/dev/null 2>&1; then
    JSHINT_BIN=jshint
elif [[ -e "./node_modules/.bin/jshint${NODE_CMD_SUFFIX}" ]]; then
    JSHINT_BIN="./node_modules/.bin/jshint${NODE_CMD_SUFFIX}"
fi

# dash does not support $'\n':
# http://forum.soft32.com/linux2/Bug-409179-DASH-Settings-IFS-work-properly-ftopict70039.html
IFS='
'

# error output
ERRORS=''
HAS_ERROR=0

# variables
INDICATOR_LENGTH=65
COUNTER=0
FILES=$(git diff-index --cached --full-index "$AGAINST_REV")
FILE_COUNT=$(echo "$FILES" | wc -l)
ERROR_INDICATOR="$(echo -e "\e[1m\e[1;31mE\e[0m")"
TMP_FILE=.git/pre-commit-tmpfile

function printcounter() {
    local indicator="$1"
    # increment counters
    COUNTER=$((COUNTER+1))
    echo -n $indicator
    if [[ $(($COUNTER % $INDICATOR_LENGTH)) == 0 ]] || [[ $COUNTER == $FILE_COUNT ]]; then
        if [[ $COUNTER == $FILE_COUNT ]]; then
            echo -n $(printf '%'$(($INDICATOR_LENGTH - $(($COUNTER % $INDICATOR_LENGTH))))'s' '')
        fi
        echo " $(printf %3s $COUNTER) / $(printf %3s $FILE_COUNT)"
    fi
}

PRECOMMIT_IGNORE_JS=$(
cat << EOF
try {
    var ignorePatterns,
        fs = require("fs"),
        minimatch = require("minimatch");
    ignorePatterns = fs.readFileSync(".precommitignore", "utf8")
        .replace(/\r/g, "")
        .split(/\n/)
        .filter(function(v) { return !!v.trim(); });

    process.exit(
        ignorePatterns.some(function(pattern) {
            return minimatch("FILE_TO_REPLACE", pattern, { nocase : true, matchBase : true });
        })
        ? 0
        : 1
    );
} catch (e) {
    process.exit(0);
}
EOF
)

# get a list of staged files
for line in $FILES; do
    # split needed values
    #oldmode=$(echo $line | cut -d' ' -f1)
    newmode=$(echo $line | cut -d' ' -f2)
    #oldsha=$(echo $line | cut -d' ' -f3)
    sha=$(echo $line | cut -d' ' -f4)
    temp=$(echo $line | cut -d' ' -f5)
    status=$(echo $temp | cut -d'	' -f1)
    filename=$(echo $temp | cut -d'	' -f2)
    ext=$(echo $filename | sed 's/^.*\.//')
    indicator='.'

    # do not check deleted files
    if [[ $status = "D" ]]; then
        printcounter D
        continue
    fi

    # do not check symlinks
    if [[ $newmode = "120000" ]]; then
        printcounter L
        continue
    fi

    if "$NODE_BIN" -e "${PRECOMMIT_IGNORE_JS/FILE_TO_REPLACE/$filename}"; then
        printcounter S
        continue
    fi

    # check the staged file content for syntax errors using jshint
    git cat-file -p $sha > $TMP_FILE

    if [[ "$ext" == "js" ]]; then
        # jscs check
        if [[ -e ./.jscsrc ]] && [[ -n "$JSCS_BIN" ]]; then
            result=$("${JSCS_BIN}" "$TMP_FILE" --config=./.jscsrc 2>&1)
            if [[ $? -ne 0 ]]; then
                HAS_ERROR=1
                indicator=$ERROR_INDICATOR
                #echo "$result"
                # Swap back in correct filenames
                ERRORS=$(echo "$ERRORS"; echo "$result" | perl -pe "s#${TMP_FILE/\//\\\\}|${TMP_FILE/\\//}#${filename}#")
            fi
        fi

        # jshint check
        if [[ -e ./.jshintrc ]] && [[ -n "$JSHINT_BIN" ]]; then
            result=$("${JSHINT_BIN}" "$TMP_FILE" --config ./.jshintrc 2>&1)
            if [[ $? -ne 0 ]]; then
                HAS_ERROR=1
                indicator=$ERROR_INDICATOR
                #echo "$result"
                # Swap back in correct filenames
                ERRORS=$(echo "$ERRORS"; echo "$result" | perl -pe "s#${TMP_FILE/\//\\\\}|${TMP_FILE/\\//}#${filename}#")
            fi
        fi
    fi

    printcounter $indicator
done
unset IFS

rm -f "$TMP_FILE"

if [[ $HAS_ERROR -eq 1 ]]; then
    echo -n "$ERRORS"
    echo ""
    exit 1
fi

Files can be skipped with a .precommitignore file in the repository root.
Also this uses the .jshintrc and .jscsrc to check if we have the ability to validate the files.

Update, fix skipped file test