vue3-reactive

对属性值直接监听

对属性进行直接监听，通过创建dep=new Set，Set内可以add添加对象类型，并确保dep为唯一的不重复对象。

示例图：

代码：

let price = 10,
  quantity = 4,
  total = 0;
let dep = new Set();
const effect = () => {
  total = price * quantity;
};
const track = () => {
  dep.add(effect);
};
const trigger = () => {
  if (dep) {
    dep.forEach(effect => effect());
  }
};
track();
trigger();
console.log('总价格total: ' + total);
quantity = 9;
trigger();
console.log('总价格total: ' + total);
price = 13;
trigger();
console.log('总价格total: ' + total);