new stream.Readable([options])

• options <Object>
  • highWaterMark <number> 在停止从底层资源读取之前存储在内部缓冲区中的最大字节数。 默认值: 16384 (16KB) 或 16 表示 objectMode 流。
  • encoding <string> 如果指定，则缓冲区将使用指定的编码解码为字符串。 默认值: null。
  • objectMode <boolean> 此流是否应表现为对象流。 这意味着 stream.read(n) 返回单个值而不是大小为 n 的 Buffer。 默认值: false。
  • emitClose <boolean> 流被销毁后是否应该触发 'close'。 默认值: true。
  • read <Function> stream._read() 方法的实现。
  • destroy <Function> stream._destroy() 方法的实现。
  • autoDestroy <boolean> 此流是否应在结束后自动调用自身的 .destroy()。 默认值: true。

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

class MyReadable extends Readable {
  constructor(options) {
    // 调用 stream.Readable(options) 构造函数。
    super(options);
    // ...
  }
}

或者，当使用 ES6 之前的风格构造函数时：

const { Readable } = require('stream');
const util = require('util');

function MyReadable(options) {
  if (!(this instanceof MyReadable))
    return new MyReadable(options);
  Readable.call(this, options);
}
util.inherits(MyReadable, Readable);

或者，使用简化的构造函数方法：

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

const myReadable = new Readable({
  read(size) {
    // ...
  }
});

• options <Object>
  • highWaterMark <number> The maximum number of bytes to store in the internal buffer before ceasing to read from the underlying resource. Default: 16384 (16KB), or 16 for objectMode streams.
  • encoding <string> If specified, then buffers will be decoded to strings using the specified encoding. Default: null.
  • objectMode <boolean> Whether this stream should behave as a stream of objects. Meaning that stream.read(n) returns a single value instead of a Buffer of size n. Default: false.
  • emitClose <boolean> Whether or not the stream should emit 'close' after it has been destroyed. Default: true.
  • read <Function> Implementation for the stream._read() method.
  • destroy <Function> Implementation for the stream._destroy() method.
  • autoDestroy <boolean> Whether this stream should automatically call .destroy() on itself after ending. Default: true.

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

class MyReadable extends Readable {
  constructor(options) {
    // Calls the stream.Readable(options) constructor.
    super(options);
    // ...
  }
}

Or, when using pre-ES6 style constructors:

const { Readable } = require('stream');
const util = require('util');

function MyReadable(options) {
  if (!(this instanceof MyReadable))
    return new MyReadable(options);
  Readable.call(this, options);
}
util.inherits(MyReadable, Readable);

Or, using the simplified constructor approach:

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

const myReadable = new Readable({
  read(size) {
    // ...
  }
});