javascript - 如何在覆盖后调用原始方法

Question

在 Javascript 中，当我覆盖 Date.prototype.toString 函数时，Date() 函数的输出不受影响并且函数保留其原始代码。

console.log(Date());
console.log(new Date().toString());

Date.prototype.toString = function() { return this.toISOString() }

console.log(Date());
console.log(new Date().toString());

"Tue Jan 26 2021 17:30:33 GMT-0500 (Eastern Standard Time)"

"Tue Jan 26 2021 17:30:33 GMT-0500 (Eastern Standard Time)"

"Tue Jan 26 2021 17:30:33 GMT-0500 (Eastern Standard Time)"

"2021-01-26T22:30:33.821Z"

测试一下 here .

---

但是，当我需要使用更复杂的 Date 类覆盖时 - 在我的例子中将时钟步长更改为 5 秒间隔 - 在我覆盖 Date.prototype.toString 之后 函数，Date() 的输出也会发生变化。由于 Date() 函数的功能不应更改，因此这是 一个不需要的和不受欢迎的变化。

console.log(Date());
console.log(new Date().toString());

(function() {
  let ___now = Date.now;
  Date = new Proxy(Date, {
    construct(target, args) {
      if (args[0] === undefined) args[0] = this.adjust()
      let date = new target(...args);
      return date;
    },
    apply(target, thisArg, argumentList) {
      return new Date(this.adjust()).toString();
    },
    adjust() {
      return 5000 * Math.floor(___now() / 5000);
    }
  });
})();
Date.prototype.toString = function() { return this.toISOString() }

console.log(Date());
console.log(new Date().toString());

"Tue Jan 26 2021 17:30:35 GMT-0500 (Eastern Standard Time)"

"Tue Jan 26 2021 17:30:35 GMT-0500 (Eastern Standard Time)"

"2021-01-26T22:30:35.000Z" "2021-01-26T22:30:35.000Z"

"2021-01-26T22:30:35.000Z" "2021-01-26T22:30:35.000Z"

测试一下 here .

---

我应该如何修改上面的代码以强制 Date() 函数使用原始的 toString() 函数，即使它被覆盖了？ toString() 的更改应该仅在显式调用时才适用，如上例所示。

Answer 1

以下应该适合您:

console.log(Date());
console.log(new Date().toString());

(function() {
  const ___now = Date.now;
  const ___toString = Date.prototype.toString;
  Date = new Proxy(Date, {
    construct(target, args) {
      if (args[0] === undefined) args[0] = this.adjust()
      let date = new target(...args);
      return date;
    },
    apply(target, thisArg, argumentList) {
      return ___toString.bind(new Date()).call();
    },
    adjust() {
      return 5000 * Math.floor(___now() / 5000);
    }
  });
})();

Date.prototype.toString = function() { return this.toISOString() }

console.log(Date());
console.log(new Date().toString());