Flatten Nested Objects

Flattening makes it easier to work with deeply nested data.

• Accessing values becomes simpler ("user.address.city" instead of obj.user.address.city).
• Many databases, APIs, and config systems prefer flat key-value pairs.
• It helps in storing, searching, and comparing data more easily.

Input: A nested JavaScript object

Output: A flattened object with keys representing the full path using dot notation.

Constraints & Edge Cases

The object can be nested inside other objects at any number of levels

• Works for both shallow and deeply nested objects.
• Example:

{ a: { b: { c: { d: "x" } } } }
→
{ "a.b.c.d": "x" }

Keys should be combined using . (dot notation)

• Nested keys are joined with a dot.
• Example:

{ address: { city: "Delhi" } }
→
{ "address.city": "Delhi" }

Values can be strings, numbers, or other primitives

• Function must handle strings, numbers, booleans, etc.
• Example:

{ age: 30, active: true }
→
{ "age": 30, "active": true }

Null values should be preserved

• If a value is null, keep it.
• Example:

{ profile: { bio: null } }
→
{ "profile.bio": null }

Empty objects should not add any extra keys

• If a nested object is empty ({}), skip it.
• Examples:

{ user: {} } → {}
{ user: { name: "John", details: {} } } → { "user.name": "John" }

• Reason: Empty objects don’t contain useful data, so avoid creating meaningless keys.

Example 1:

Input:

let user = {
    name: 'John',
    address: {
        country: 'India',
        state: 'India',
        education: {
            school: "APS",
            year: 2021
        }
    }
};

Output:

{
  'user.name': 'John',
  'user.address.country': 'India',
  'user.address.state': 'India',
  'user.address.education.school': 'APS',
  'user.address.education.year': 2021
}

Example 2:

Input:

const data = {
  user: {
    name: "Bob",       
    age: 25,          
    contact: {
      email: null,    
      phone: "999"
    }
  },
  empty: {},           
  active: true         
};

Output:

{
  "root.user.name": "Bob",
  "root.user.age": 25,
  "root.user.contact.email": null,
  "root.user.contact.phone": "999",
  "root.active": true
}