对象模式双工流

¥Object mode duplex streams

对于 Duplex 流，可以分别使用 readableObjectMode 和 writableObjectMode 选项为 Readable 或 Writable 端专门设置 objectMode。

¥For Duplex streams, objectMode can be set exclusively for either the Readable or Writable side using the readableObjectMode and writableObjectMode options respectively.

例如，在下面的示例中，创建了一个新的 Transform 流（这是一种 Duplex 流），它具有对象模式 Writable 端，该端接受在 Readable 端转换为十六进制字符串的 JavaScript 数字。

¥In the following example, for instance, a new Transform stream (which is a type of Duplex stream) is created that has an object mode Writable side that accepts JavaScript numbers that are converted to hexadecimal strings on the Readable side.

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

// All Transform streams are also Duplex Streams.
const myTransform = new Transform({
  writableObjectMode: true,

  transform(chunk, encoding, callback) {
    // Coerce the chunk to a number if necessary.
    chunk |= 0;

    // Transform the chunk into something else.
    const data = chunk.toString(16);

    // Push the data onto the readable queue.
    callback(null, '0'.repeat(data.length % 2) + data);
  },
});

myTransform.setEncoding('ascii');
myTransform.on('data', (chunk) => console.log(chunk));

myTransform.write(1);
// Prints: 01
myTransform.write(10);
// Prints: 0a
myTransform.write(100);
// Prints: 64 拷贝