Blob 对象和 MessageChannel

一旦创建了 <Blob> 对象，则它就可以通过 MessagePort 发送给多个目标，而无需传输或立即复制数据。 只有在调用 arrayBuffer() 或 text() 方法时才会复制 Blob 包含的数据。

const { Blob } = require('buffer');
const blob = new Blob(['hello there']);
const { setTimeout: delay } = require('timers/promises');

const mc1 = new MessageChannel();
const mc2 = new MessageChannel();

mc1.port1.onmessage = async ({ data }) => {
  console.log(await data.arrayBuffer());
  mc1.port1.close();
};

mc2.port1.onmessage = async ({ data }) => {
  await delay(1000);
  console.log(await data.arrayBuffer());
  mc2.port1.close();
};

mc1.port2.postMessage(blob);
mc2.port2.postMessage(blob);

// 发布后 Blob 仍然可用。
data.text().then(console.log);

Once a <Blob> object is created, it can be sent via MessagePort to multiple destinations without transfering or immediately copying the data. The data contained by the Blob is copied only when the arrayBuffer() or text() methods are called.

const { Blob } = require('buffer');
const blob = new Blob(['hello there']);
const { setTimeout: delay } = require('timers/promises');

const mc1 = new MessageChannel();
const mc2 = new MessageChannel();

mc1.port1.onmessage = async ({ data }) => {
  console.log(await data.arrayBuffer());
  mc1.port1.close();
};

mc2.port1.onmessage = async ({ data }) => {
  await delay(1000);
  console.log(await data.arrayBuffer());
  mc2.port1.close();
};

mc1.port2.postMessage(blob);
mc2.port2.postMessage(blob);

// The Blob is still usable after posting.
data.text().then(console.log);