Vue computed与watch用法区分

data: {
    firstName: 'one',
    lastName: 'two'
  },
//计算方法
computed: {
allname:{
	//回调函数 当需要读取当前属性值是执行，根据相关数据计算并返回当前属性的值
	get() {//
		return this.firstName + ' ' + this.lastName
	},
	//监视当前属性值的变化，当属性值发生变化时执行，更新相关的属性数据
	set(val){
		const names = val.split(' ');
		this.firstName = names[0];
        this.lastName = names[1];
	}
}
},

computed:{
    stateDemo(){
        return this.$store.state.demoState;
    }
}
watch:{
    stateDemo(){
        console.log('vuex变化啦')
    }
}

props:['listShop'],
    data(){
      return{}
    },
    created(){
      this.listShop=30
}

//不会有任何报错,也不会影响父组件!
	props:['listShop'],
    data(){
      return{
        listShopChild:this.listShop //改变指向
      }
    },
    created(){
      this.listShopChild=30
    }

//数组深度克隆:
var x = [1,2,3];
var y = [];
for (var i = 0; i < x.length; i++) {
    y[i]=x[i];
}
console.log(y);  //[1,2,3]
y.push(4);
console.log(y);  //[1,2,3,4]
console.log(x);  //[1,2,3]
//对象深度克隆:
var x = {a:1,b:2};
var y = {};
for(var i in x){
    y[i] = x[i];
}
console.log(y);  //Object {a: 1, b: 2}
y.c = 3;
console.log(y);  //Object {a: 1, b: 2, c: 3}
console.log(x);  //Object {a: 1, b: 2}
//函数深度克隆
//为什么函数可以直接赋值克隆?
//由于函数对象克隆之后的对象会单独复制一次并存储实际数据，因此并不会影响克隆之前的对象。所以采用简单的复制“=”即可完成克隆。
var x = function(){console.log(1);};
var y = x;
y = function(){console.log(2);};
x();  //1
y();  //2

//方法三
const obj1 = JSON.parse(JSON.stringify(obj));

//方法四
computed:{
  listShopChild(){
    return this.listShop
   }
}