Indent size preference on my JavaScript source code. I preferred to choose indent size with 2 spaces.

indent-size-2.js

/**
 * A middleware to check the requested content type.
 */
module.exports.acceptedFormat = function () {

  return function (req, res, next) {

    res.format({
      'application/json': function () {
        next();
      },
      'application/xml': function () {
        next();
      },
      'default': function () {
        res.send(406, 'Sorry, we only provide resources in JSON and XML.');
      }
    });
  };
};

indent-size-4.js

/**
 * A middleware to check the requested content type.
 */
module.exports.acceptedFormat = function () {
    return function (req, res, next) {

        res.format({
            'application/json': function () {
                next();
            },
            'application/xml': function () {
                next();
            },
          'default': function () {
              res.send(406, 'Sorry, we only provide resources in JSON and XML.');
            }
        });
    };
};