设计模式----单例模式核心思想是确保一个类只对应一个实例。 1. 利用闭包来 2. 利用es6 class的静态属性

核心思想是确保一个类只对应一个实例。

1. 利用闭包来

function Base() {}

Base.prototype.test = 1;
const single = (function () {  
    let instance = null;  
        return function () {   
             if (!instance) {      
                instance = new Base()    
              }    
                return instance 
             }})()
            const a = single();
            const b = single()
            console.log(a === b)
            a.test = 2;
            console.log(b.test)

2. 利用es6 class的静态属性

class Base {  
    static getInstace() {   
         if (!Base.instance) {     
                 Base.instance = new Base()   
             }    
            return Base.instance  }  
        }

const a = Base.getInstace();
const b = Base.getInstace()
console.log(a === b)
a.test = 2;
console.log(b.test)

3. 实际应用模态框在构造函数中创建单例模式

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