const fs = require("fs");
const { pipeline, Transform } = require("stream");

const uppercase = new Transform({
  transform(chunk, encoding, callback) {
    // Data processing
    callback(null, chunk.toString().toUpperCase());
  },
});

pipeline(
  fs.createReadStream("./file.txt"),
  uppercase,
  fs.createWriteStream("./newFile.txt"),
  (err) => {
    if (err) {
      console.error("Pipeline failed.", err);
    } else {
      console.log("Pipeline succeeded.");
    }
  }
);