JavaScript实现的字典

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字典中存储的是[key，value]，其中键名是用来查询特定的元素的。字典和集合很相似，只是集合以[value,value]的格式来存储数据的。字典也叫作映射。

下面通过一个实际例子来创建并且使用一下字典。

function Dictionary(){

var items = {};

this.set = function(key, value){

items[key] = value; //以键作为索引来存储数据

};

this.remove = function(key){

if (this.has(key)){

delete items[key];

return true;

}

return false;

};

this.has = function(key){

return items.hasOwnProperty(key);

//return value in items;

};

this.get = function(key) {

return this.has(key) ? items[key] : undefined;

};

this.clear = function(){

items = {};

};

this.size = function(){

return Object.keys(items).length;

};

this.keys = function(){

return Object.keys(items);

};

this.values = function(){

var values = [];

for (var k in items) {

if (this.has(k)) {

values.push(items[k]);

}

return values;

};

this.each = function(fn) {

for (var k in items) {

if (this.has(k)) {

fn(k, items[k]);

}

};

this.getItems = function(){

return items;

}

简单地使用字典

var dictionary = new Dictionary();

dictionary.set('Gandalf', 'gandalf@email.com');

dictionary.set('John', 'johnsnow@email.com');

dictionary.set('Tyrion', 'tyrion@email.com');

console.log(dictionary.has('Gandalf'));

console.log(dictionary.size());

console.log(dictionary.keys());

console.log(dictionary.values());

console.log(dictionary.get('Tyrion'));

dictionary.remove('John');

console.log(dictionary.keys());

console.log(dictionary.values());

console.log(dictionary.getItems()); //打印输出items对象的内部结构

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