Get cell data-type
@param string {String}
@returns {String} data-type
function(string) {
      if (!string) return "";
      var types = this.typeConfig;
      if (~string.indexOf(types.string.defaultClass)) {
        return _TYPE.STRING;
      } else if (~string.indexOf(types.number.defaultClass)) {
        return _TYPE.NUMBER;
      } else if (~string.indexOf(types.boolean.defaultClass)) {
        return _TYPE.BOOLEAN;
      } else if (~string.indexOf(types.date.defaultClass)) {
        return _TYPE.DATE;
      } else {
        return "";
      }
    }