hw-1.js

const fs = require('fs');

const writeFile = async (data, fileName) => {
  // 你要寫的部分
  return new Promise((resolve, reject) => {
    fs.writeFile(fileName, data, (err) => {
      if (err) {
        reject(err);
      }
      resolve();
    });
  });
};

(async () => {
  await writeFile('ABC', 'test.txt');
})();