var Place = function (title) {
		    this.title = title;  
		};
		
		//例項化Place物件
		var kitchen = new Place("The Kitchen");
		var dungeon = new Place("The Dungeon");
		
		var exits = {};
		//exits物件的north屬性對應的值是一個例項化之後的kitchen物件
		exits["north"] = kitchen;
		exits["the trapdoor"] = dungeon;
		
		//將物件exits轉化為陣列的形式
		var keys = Object.keys(exits);
		//對陣列遍歷
		keys.forEach(function (key) {
		    console.log(key + " goes to " + exits[key].title);
		});