使用原型、类、以及访问器克隆对象时的注意事项

🌐 Considerations when cloning objects with prototypes, classes, and accessors

由于对象克隆使用 HTML 结构化克隆算法，非可枚举属性、属性访问器和对象原型不会被保留。特别是，Buffer 对象在接收端会被读取为普通的 Uint8Array，而 JavaScript 类的实例将被克隆为普通的 JavaScript 对象。

🌐 Because object cloning uses the HTML structured clone algorithm, non-enumerable properties, property accessors, and object prototypes are not preserved. In particular, Buffer objects will be read as plain Uint8Arrays on the receiving side, and instances of JavaScript classes will be cloned as plain JavaScript objects.

const b = Symbol('b');

class Foo {
  #a = 1;
  constructor() {
    this[b] = 2;
    this.c = 3;
  }

  get d() { return 4; }
}

const { port1, port2 } = new MessageChannel();

port1.onmessage = ({ data }) => console.log(data);

port2.postMessage(new Foo());

// Prints: { c: 3 } 拷贝

此限制适用于许多内置对象，例如全局的 URL 对象：

🌐 This limitation extends to many built-in objects, such as the global URL object:

const { port1, port2 } = new MessageChannel();

port1.onmessage = ({ data }) => console.log(data);

port2.postMessage(new URL('https://example.org'));

// Prints: { } 拷贝