mounted() {
    const { nums } = this.price;
    Object.freeze(nums);
    this.proxy = new Proxy(
      {},
      {
        get(target, key) {
          if (key === "up") {
            return [].concat(nums).sort((a, b) => a - b);
          } else if (key === "down") {
            return [].concat(nums).sort((a, b) => b - a);
          } else {
            return nums;
          }
        },
        set() {
          return false;
        },
      }
    );
    this.list = this.proxy.default;
    console.log(this.proxy.up);
  },

console.log(this.proxy.up);打印出来的为什么是undefined