js design pattern - singleton

Design pattern - singleton

In some scenarios, we will encounter some of the more difficult objects (such as only allowed a pop, allowing only one leader) and so on. This time you need to use a singleton

var Dog = function(name) {
	this.name = name
	this._instance = null
}

Dog.createDog = function(newName) {
	if(this._instance){
		this._instance.name = newName
	}else{
		this._instance = new Dog(newName)
	}
	return this._instance
}	

let husky = Dog.createDog('husky')
let shiba = Dog.createDog('shiba')
console.log(husky.name) // shiba
console.log(shiba.name) // shiba
console.log(husky === shiba) // true

The above case is the easiest mode of single-case model