nodejs stream 创建读写流

const fs = require("fs");
const { Writable, Readable, Duplex, Transform } = require("stream");// 双向流
const inoutStream = new Duplex({  // 获取写入的数据
  write(chunk, encoding, callback) {
    console.log(chunk.toString());
    callback();
  },  // 一直读直到null为止
  read(size) {
    this.push(String.fromCharCode(this.currentCharCode++));
    if (this.currentCharCode > 90) this.push(null);
  },
});inoutStream.currentCharCode = 65;
process.stdin.pipe(inoutStream).pipe(inoutStream);const sizeStream = new Transform({
  readableObjectMode: true,
  writableObjectMode: true,  // 转换流，可以改变数据
  transform(chunk, encoding, callback) {
    this.push(chunk.toString() + `\r\n // size(${chunk.length})`);
    callback();
  },
});const outStream = new Writable({
  write(chunk, encoding, callback) {
    console.log(chunk.toString("utf-8"));
    callback();
  },
});fs.createReadStream("./x.txt").pipe(sizeStream).pipe(outStream);

See also:

• https://www.freecodecamp.org/news/node-js-streams-everything-you-need-to-know-c9141306be93/