JavaScript 实现枚举类型

标签：javascript

function enumeration(namesToValues) {
	var enumeration = function() { throw "Can't Instantiate Enumeration"}

	var proto = enumeration.prototype = {
		constructor: enumeration,
		toString: function() { return this.name; },
		valueOf: function() { return this.value; },
		toJSON: function() { return this.name; }
	};

	enumeration.values = [];

	for(name in namesToValues) {
		var e = inherit(proto);
		e.name = name;
		e.value = namesToValues[name];
		enumeration[name] = e;
		enumeration.values.push(e);
	}

	enumeration.foreach = function(f, c) {
		for (var i = 0; i < this.values.length; i++) {
			f.call(c, this.values[i]);
		};
	};

 	Object.freeze(enumeration.values);
 	Object.freeze(enumeration);
	return enumeration;
}

function inherit(p) {
  if (p == null) throw TypeError();
  if (Object.create)
    return Object.create(p);
  var t = typeof p;
  if (t !== "object" && t !== "function") throw TypeError();
  function f() {};
  f.prototype = p;
  return new f();
}

var Coin = enumeration({Penny: 1, Nickel:5, Dime:10, Quarter:25});
var c = Coin.Dime;
c instanceof Coin;
c.constructor == Coin;

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JavaScript 实现枚举类型

标签：javascript

原文地址：http://blog.csdn.net/bzq9012/article/details/38729987