单例模式

[LittlebearHat]

个人写法不习惯用class语法糖

const danli = function (name) {
  this.name = name;
  this.instance = null;
};
danli.prototype.getName = function () {
  console.log(this.name);
};
danli.getInstance = function (ret) {
  if (!this.instance) {
    this.instance = new danli(ret);
    //假如为null，创建一个构造函数，此时instance标记不为空，不用进行二次创建
  }
  return this.instance;
};
let a = danli.getInstance("a");
let b = danli.getInstance("b");
a.getName();
b.getName();
console.log(a === b); //他俩相同，因为没有二次创建

[vuemenow]

ES6 class实现

class Singleton {
    constructor(name, age) {
        if (!Singleton.instance) {
            this.name = name
            this.age = age
            Singleton.instance = this
        }
        return Singleton.instance
    }
}

console.log(new Singleton("Taobao", 18) === new Singleton("Baidu", 15)) // true