8、字典

function Dictionary(){this.dataStore = new Array();this.add = add;this.find = find;this.remove = remove;this.showAll = showAll;this.count = count;this.clear = clear;}function add(key, value){this.dataStore[key] = value;}function find(key){return this.dataStore[key];}function remove(key){delete this.dataStore[key];}function showAll(){// 调用Object类的keys()方法可以返回传入参数中存储的所有键var datakeys = Array.prototype.slice.call(Object.keys(this.dataStore));for(var key in datakeys){log(datakeys[key] + " -> " + this.dataStore[datakeys[key]]);}log("------");for(var key in datakeys.sort()){log(datakeys[key] + " -> " + this.dataStore[datakeys[key]]);}}// 当键的类型为字符串时，length属性就不管用了function count(){var n = 0;for(var key in Object.keys(this.dataStore)){++n;}return n;}function clear(){Object.keys(this.dataStore).forEach(function(key){delete this.dataStore[key];}, this);}var log = console.log;var pbook = new Dictionary();pbook.add("Late", "123");pbook.add("Autumn", "456");pbook.add("Eric", "789");log("All: " + pbook.count());pbook.showAll();log("\n");log("查找Eric的内容: ");log("Eric's number: " + pbook.find("Eric"));log("\n");log("删除Eric: ");pbook.remove("Eric");pbook.showAll();log("\n");pbook.clear();log("All: " + pbook.count());