Q239- Implement a function to flatten deeply nested objects (not array).

Q239 — Flatten a Deeply Nested Object

✅ Goal:

Convert this 👇

const obj = {
  user: {
    name: "Teekam",
    address: {
      city: "Delhi",
      pin: 110001
    }
  },
  skills: {
    frontend: {
      react: true
    }
  }
};

Into this 👇

{
  "user.name": "Teekam",
  "user.address.city": "Delhi",
  "user.address.pin": 110001,
  "skills.frontend.react": true
}

---

✅ Flatten Function (Handles Deep Objects)

function flattenObject(obj, parentKey = "", result = {}) {
  for (let key in obj) {
    const newKey = parentKey ? `${parentKey}.${key}` : key;

    if (typeof obj[key] === "object" && obj[key] !== null && !Array.isArray(obj[key])) {
      flattenObject(obj[key], newKey, result);
    } else {
      result[newKey] = obj[key];
    }
  }
  return result;
}

---

🧪 Example Usage

const output = flattenObject(obj);
console.log(output);

Output:

{
  "user.name": "Teekam",
  "user.address.city": "Delhi",
  "user.address.pin": 110001,
  "skills.frontend.react": true
}

---

💡 How It Works

• Loops through object keys
• If value is another object → recursively flatten it
• Otherwise add it to result
• Joins nested keys using "."

---

🎯 Real-Time Use Cases

• Converting nested JSON to database fields
• Form data processing
• Logging/analytics
• Creating dot-notation paths for MongoDB
• Working with nested config files