function compare( a, operator, b ) {
    // When parameter omited
    if ( isNaN( b ) ) {
      return true;
    }
    switch( operator ) {
      case "eq":
        return a === b;
      case "gt":
        return a > b;
      default:
        return a < b;
    }
  }
@param {Number} a
@param {String} operator
@param {Number} b
@returns {Boolean}