enum.js

/*globals module */
!(function(){
  var exports;
  if( typeof window !== 'undefined'){
    exports = window;
  } else if( typeof module !== 'undefined' ){
    exports = module.exports;
  } else {
    console.warn("I don't know where to export to....Enums.js");
    exports = {};
  }

exports.Enum = (function () {
  "use strict";
  var Enum = function ( enums ) {
    var i,
        keys = [],
        values = [],
        length = 0;

//  if(!(enums instanceof Array)){
//    throw new SyntaxError('Enum input must be an Array');
//  }

    if ( enums instanceof Array ) {
      for ( i = 0 ; i < enums.length ; i++ ) {
        try {
          Object.defineProperty(
            this,
            enums[i],
            {
              configurable: false,
              enumerable:   true,
              value:        i,
              writable:     false
            }
          );
          ++length;
          values.push(i);
          keys.push(enums[i]);
        } catch (e) {
          throw new TypeError('Enum Constructor Failure, you must pass a set of unique keys.');
        }
      }
    } else if ( enums instanceof Object ) {
      for ( i in enums ) {
        if ( enums.hasOwnProperty(i) ) {
          if ( values.lastIndexOf(enums[i]) !== -1 ) {
            throw new TypeError('Enum Constructor Failure, you must pass a unique value for each key');
          }
          try {
            Object.defineProperty(
              this,
              i,
              {
                configurable: false,
                enumerable:   true,
                value:        enums[i],
                writable:     false
              }
            );
            ++length;
            values.push(enums[i]);
            keys.push(i);
          } catch (e) {
            throw new TypeError('Enum Constructor Failure.');
          }
        }
      }
    }

    Object.defineProperty(this, 'length', {
      configurable: false,
      enumerable:   false,
      value:        length,
      writable:     false
    });

//    Object.defineProperty(this, 'keys', {
//      configurable: false,
//      enumerable:   false,
//      value:        keys,
//      writable:     false
//    });
//    Object.defineProperty(this, 'values', {
//      configurable: false,
//      enumerable:   false,
//      value:        values,
//      writable:     false
//    });

    return Object.freeze(this);
  };

  // Prototype Functions
  Object.defineProperties(Enum.prototype, {
    /*'length':{
      configurable: false,
      enumerable:   false,
      get:          function () {
        var count = 0;
        for ( var prop in this ){
          ++count;
        }
        return count;
        //return this.keys.length;
      }
    },*/
    'keys':{
      configurable: false,
      enumerable:   false,
      get:          function () {
        var keys = [];
        for ( var prop in this ){
          if ( this.hasOwnProperty(prop) ){
            keys.push(prop);
          }
        }
        return keys;
      }   
    },
    'values':{
      configurable: false,
      enumerable:   false,
      get:          function () {
        var values = [];
        for ( var prop in this ){
          if ( this.hasOwnProperty(prop) ){
            values.push(this[prop]);
          }
        }
        return values;
      }
    },
    'toString':{
      configurable: false,
      enumerable:   false,
      writable:     false,
      value:        function(){return '[object Enum]';}
    }
  });

  // Export
  return Enum;

})();

})();