Read/Write file with promises in node js

readWriteFileNodeJsPromises.js

const { promises } = require("fs");

const { readFile, writeFile } = promises;
const input = "src/index.js";
const output = "src/index2.js";

const errorHandler = (error) => {
  console.error(error.message);
  process.exit(1);
};

readFile(input)
  .then((fileBuffer) => {
    console.log(fileBuffer.toString());
    writeFile(output, fileBuffer.toString().split("").reverse().join(""))
      .then((r) => {
        console.log("Saved file", r);
      })
      .catch(errorHandler);
  })
  .catch(errorHandler);