stream.Readable.from(iterable[, options])

• iterable <Iterable> 实现 Symbol.asyncIterator 或 Symbol.iterator 可迭代协议的对象。 如果传入空值，则触发 'error' 事件。
• options <Object> 提供给 new stream.Readable([options]) 的选项。 默认情况下，Readable.from() 会将 options.objectMode 设置为 true，除非通过将 options.objectMode 设置为 false 来明确选择退出。
• 返回: <stream.Readable>

一个从迭代器中创建可读流的实用方法。

const { Readable } = require('node:stream');

async function * generate() {
  yield 'hello';
  yield 'streams';
}

const readable = Readable.from(generate());

readable.on('data', (chunk) => {
  console.log(chunk);
});

出于性能原因，调用 Readable.from(string) 或 Readable.from(buffer) 不会迭代字符串或缓冲区以匹配其他流语义。

如果包含承诺的 Iterable 对象作为参数传递，可能会导致未处理的拒绝。

const { Readable } = require('node:stream');

Readable.from([
  new Promise((resolve) => setTimeout(resolve('1'), 1500)),
  new Promise((_, reject) => setTimeout(reject(new Error('2')), 1000)), // 未处理的拒绝
]);

• iterable <Iterable> Object implementing the Symbol.asyncIterator or Symbol.iterator iterable protocol. Emits an 'error' event if a null value is passed.
• options <Object> Options provided to new stream.Readable([options]). By default, Readable.from() will set options.objectMode to true, unless this is explicitly opted out by setting options.objectMode to false.
• Returns: <stream.Readable>

A utility method for creating readable streams out of iterators.

const { Readable } = require('node:stream');

async function * generate() {
  yield 'hello';
  yield 'streams';
}

const readable = Readable.from(generate());

readable.on('data', (chunk) => {
  console.log(chunk);
});

Calling Readable.from(string) or Readable.from(buffer) will not have the strings or buffers be iterated to match the other streams semantics for performance reasons.

If an Iterable object containing promises is passed as an argument, it might result in unhandled rejection.

const { Readable } = require('node:stream');

Readable.from([
  new Promise((resolve) => setTimeout(resolve('1'), 1500)),
  new Promise((_, reject) => setTimeout(reject(new Error('2')), 1000)), // Unhandled rejection
]);