/* Person 类 */

class Person {

constructor(name, age) {

this.name = name

this.age = age

}

}

/* IIFE */

// const Singleton = (function() {

// let _instance = null

// const ProxySingleton = function(name, age) {

// if(_instance) return _instance

// _instance = new Person(name, age)

// return _instance

// }

// ProxySingleton.getInstance = function(name, age) {

// if (_instance) return _instance

// _instance = new Singleton(name, age)

// return _instance

// }

// return ProxySingleton

// })()

// const person1 = new Singleton('张小帅', 25) // '张小帅', 25

// const person2 = new Singleton('李小美', 23) // '张小帅', 25

// console.log('person1 :', person1);

// console.log('person2 :', person2);

/* Proxy */

function Singleton(FuncClass) {

let _instance

return new Proxy(FuncClass, {

construct(target, args) {

return _instance || (_instance = Reflect.construct(FuncClass, args)) // 使用 new FuncClass(...args) 也可以

}

})

}

const PersonInstance = Singleton(Person)

const person1 = new PersonInstance('张小帅', 25) // '张小帅', 25

const person2 = new PersonInstance('李小美', 23) // '张小帅', 25

console.log('person1 === person2 :', person1 === person2); // true

// 饿汉式

const HungrySingleton = (function() {

const _instance = new FuncClass()

return function() {

return _instance

}

})()

// 懒汉式

const LazySingleton = (function() {

let _instance = null

return function() {

return _instance || (_instance = new FuncClass())

}

})()