stringify an object with functions

stringify-object.js

module.exports = function stringifyObject(obj) {
  var
    ret = '{',
    keys = [],
    _key = '';
  for(var key in obj) {
    _key += '\'' + key + '\' : ';
    if (typeof obj[key] === 'object') {
      _key += stringifyObject(obj[key]);
    } else if (obj[key]) {
      _key += obj[key].toString();
    } else {
      _key += 'undefined';
    }
    keys.push(_key);
    _key = '';
  }
  ret += keys.join(',');
  ret += '}';
  return ret;
};