port.postMessage(value[, transferList])

• value <any>
• transferList 对象数组[]

将一个 JavaScript 值发送到此通道的接收端。value 以与 HTML 结构化克隆算法 兼容的方式进行传输。

【Sends a JavaScript value to the receiving side of this channel. value is transferred in a way which is compatible with the HTML structured clone algorithm.】

特别是，与 JSON 的显著区别如下：

【In particular, the significant differences to JSON are:】

• value 可能包含循环引用。
• value 可能包含内置 JS 类型的实例，例如 RegExp、BigInt、Map、Set 等。
• value 可能包含类型化数组，这些数组可以使用 ArrayBuffer 或 SharedArrayBuffer。
• value 可能包含 WebAssembly.Module 个实例。
• value 可能不包含除以下之外的本地（C++ 支撑的）对象：
  • <CryptoKey>们,
  • <FileHandle>们,
  • <Histogram>们,
  • <KeyObject>们,
  • <MessagePort>们,
  • <net.BlockList>，
  • <net.SocketAddress>们,
  • <X509Certificate>们。

import { MessageChannel } from 'node:worker_threads';
const { port1, port2 } = new MessageChannel();

port1.on('message', (message) => console.log(message));

const circularData = {};
circularData.foo = circularData;
// Prints: { foo: [Circular] }
port2.postMessage(circularData);'use strict';

const { MessageChannel } = require('node:worker_threads');
const { port1, port2 } = new MessageChannel();

port1.on('message', (message) => console.log(message));

const circularData = {};
circularData.foo = circularData;
// Prints: { foo: [Circular] }
port2.postMessage(circularData);拷贝

transferList 可能是 <ArrayBuffer>、MessagePort 和 FileHandle 对象的列表。
传输后，它们在通道的发送端不再可用（即使它们不包含在 value 中）。与 子进程 不同的是，目前不支持传输网络套接字等句柄。

如果 value 包含 <SharedArrayBuffer> 个实例，这些实例可以从任一线程访问。它们不能列在 transferList 中。

【If value contains <SharedArrayBuffer> instances, those are accessible from either thread. They cannot be listed in transferList.】

value 仍可能包含未在 transferList 中的 ArrayBuffer 实例；在这种情况下，底层内存是被复制而不是移动的。

import { MessageChannel } from 'node:worker_threads';
const { port1, port2 } = new MessageChannel();

port1.on('message', (message) => console.log(message));

const uint8Array = new Uint8Array([ 1, 2, 3, 4 ]);
// This posts a copy of `uint8Array`:
port2.postMessage(uint8Array);
// This does not copy data, but renders `uint8Array` unusable:
port2.postMessage(uint8Array, [ uint8Array.buffer ]);

// The memory for the `sharedUint8Array` is accessible from both the
// original and the copy received by `.on('message')`:
const sharedUint8Array = new Uint8Array(new SharedArrayBuffer(4));
port2.postMessage(sharedUint8Array);

// This transfers a freshly created message port to the receiver.
// This can be used, for example, to create communication channels between
// multiple `Worker` threads that are children of the same parent thread.
const otherChannel = new MessageChannel();
port2.postMessage({ port: otherChannel.port1 }, [ otherChannel.port1 ]);'use strict';

const { MessageChannel } = require('node:worker_threads');
const { port1, port2 } = new MessageChannel();

port1.on('message', (message) => console.log(message));

const uint8Array = new Uint8Array([ 1, 2, 3, 4 ]);
// This posts a copy of `uint8Array`:
port2.postMessage(uint8Array);
// This does not copy data, but renders `uint8Array` unusable:
port2.postMessage(uint8Array, [ uint8Array.buffer ]);

// The memory for the `sharedUint8Array` is accessible from both the
// original and the copy received by `.on('message')`:
const sharedUint8Array = new Uint8Array(new SharedArrayBuffer(4));
port2.postMessage(sharedUint8Array);

// This transfers a freshly created message port to the receiver.
// This can be used, for example, to create communication channels between
// multiple `Worker` threads that are children of the same parent thread.
const otherChannel = new MessageChannel();
port2.postMessage({ port: otherChannel.port1 }, [ otherChannel.port1 ]);拷贝

消息对象会被立即克隆，并且在发布后可以修改而不会产生副作用。

【The message object is cloned immediately, and can be modified after posting without having side effects.】

有关此 API 背后的序列化和反序列化机制的更多信息，请参见 node:v8 模块的序列化 API。

【For more information on the serialization and deserialization mechanisms behind this API, see the serialization API of the node:v8 module.】