sorting

    (function() {
      // default comparing functions for specified types
      // in config can be defined custom one
      var dataTypes = {
        'string': function(strA, strB) {
          return strA.localeCompare(strB);
        },
        'number': function(numA, numB) {
          return numA - numB;
        },
        'enum': function(valA, valB, config) {
          return config.order.indexOf(valA) - config.order.indexOf(valB);
        }
      };

      var getDirNumber = (function() {
        var map = {
          'asc': 1,
          'dsc': -1
        };
        return function(dir) {
          // return direction of sorting
          // dont sort (0) if its not fit to any direction
          return dir && map[dir] || 0;
        };
      })();

      var getCompareFn = function(rule, sortingConfig) {
        var dataType = sortingConfig.properties[rule.property].dataType;
        // custom function can be set in rule, or its taken from custom dataTypes, and default ones
        var comparingFn = rule.custom || sortingConfig.dataTypes[dataType] || dataTypes[dataType];

        return function(itemA, itemB) {
          return getDirNumber(rule.dir) * comparingFn(
            itemA[rule.property],
            itemB[rule.property],
            rule.config
          );
        };
      };

      return function(data, sortingRules, sortingConfig) {
        var l = sortingRules.length;

        data.sort(function(itemA, itemB) {
          var compareResult = 0;
          for (var i = 0; i < l; ++i) {
            compareResult = getCompareFn(sortingRules[i], sortingConfig)(itemA, itemB);
            if (compareResult !== 0) {
              break;
            }
          }
          return compareResult;
        });
      };
    })()