code: function formatParams_(params) {
    var query = '';
    if (params) {
      params.f = params.f || 'json';
      for (var x in params) {
        if (params.hasOwnProperty(x) && params[x] !== null && params[x] !== undefined) { // wont sent undefined.
          //jslint complaint about escape cause NN does not support it.
          var val = formatRequestString_(params[x]); 
          query += (query.length > 0?'&':'')+(x + '=' + (escape ? escape(val) : encodeURIComponent(val)));
        }
      }
    }
    return query;
  }
docs: Format params to URL string
  @param {Object} params