Setup Linter for JavaScript

In the following document we will install one of the most popular linters for JavaScript: ESLint

ESLint is a tool for identifying and reporting on patterns found in ECMAScript/JavaScript code.

Install ESLint on Bitbucket Host #

Follow the official instruction of eslint and make sure to run eslint --init and push .eslintrc to your repository:

Most probably, your host with Bitbucket doesn’t have nodejs/npm installed, so you need to install it yourself, follow the following instructions:

Installing Node.js via package manager

Setting up Hook #

Place the following script under the <bitbucket-home-dir>/external-hooks/hook-eslint path:



while read from_ref to_ref ref_name; do
    echo "eslint checking changeset $from_ref → $to_ref"

    # create temporary directory to extract pre received files
    TEMPDIR=$(mktemp -d)

    # retrieving list of files from diff (added/modified)
    files=($(git show --name-only --diff-filter=AM $from_ref..$to_ref | grep '\.js$'))
    if [[ ${#files} -eq 0 ]]; then
        echo "eslint: no js files found, skipping"

        # removing temporary directory
        rm -rf "$TEMPDIR"

        # nothing to do if not js files

    # obtaining contents of modified/added files in commit into temporary
    # directory

    git cat-file -p "$to_ref:.eslintrc.js" > "$TEMPDIR/.eslintrc.js"
    for file in "${files[@]}"; do
        mkdir -p "$TEMPDIR/$(dirname "$file")"
        git cat-file -p "$to_ref:${file}" > "$TEMPDIR/$file"

    # changing directory to TEMPDIR to save path of filenames in output of linter
    cd "$TEMPDIR"

    # running linter against files in that commit
    eslint "${files[@]}"
    if [[ $? -ne 0 ]]; then
        echo "js: changeset $from_ref → $to_ref has not passed checks"

    rm -rf "$TEMPDIR"

if $failed; then
    exit 1

Navigate to your repository page → Repository settings → Hooks, and enable the External Pre Receive Hook with the following parameters:

  • Executable: hook-eslint
  • Safe mode:
  • Positional arguments: leave it empty

Test your hook by pushing invalid javascript code, you should get an error if your code syntax is incorrect:

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