append to a json file in typescript

index.ts
import fs from 'fs';

const data = {name: 'John', age: 25};

fs.readFile('./data.json', 'utf-8', (err, jsonString) => {
  if (err) {
    console.log(`Error reading file from disk: ${err}`);
    return;
  }
  try {
    const jsonObject = JSON.parse(jsonString);
    jsonObject.push(data);
    fs.writeFile('./data.json', JSON.stringify(jsonObject), 'utf-8', (err) => {
      if (err) {
        console.log(`Error writing file: ${err}`);
      } else {
        console.log(`Data added to file`);
      }
    });
  } catch (err) {
    console.log(`Error parsing JSON string: ${err}`);
  }
});
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