Inspecter un objet en Javascript

function inspect(obj, maxLevels, level) {
  var str = '', type, msg;
  
  if(level == null)  level = 0;
  
  if(maxLevels == null) maxLevels = 1;
  
  if(maxLevels < 1) return 'Error: Levels number must be > 0';
  
    if(obj == null) return 'Error: Object NULL';

    for(property in obj) {
      try {
          type = typeof(obj[property]);
          str += property + ( (obj[property]==null)?(': null'):(''));
          str += ' (' + type + ')';
          if((type == 'object') && (obj[property] != null) && (level+1 < maxLevels))
          str += inspect(obj[property], maxLevels, level+1);
      } catch(err) {
        if(typeof(err) == 'string') msg = err;
        else if(err.message)        msg = err.message;
        else if(err.description)    msg = err.description;
        else                        msg = 'Unknown';
        str += '(Error) ' + property + ': ' + msg + '';
      }
    }

    return str;
}