Extract Object Keys

extractObjectKeys

Extracts the keys of an object with proper typing.

Import

import { extractObjectKeys } from 'nhb-toolbox';

Function Signatures

extractObjectKeys<T extends GenericObject>(obj: T): Array<keyof T>;

extractObjectKeys<T extends GenericObject>(obj: T, tuple: true): Tuple<keyof T>;

Aliases

• extractKeys - Alias for extractObjectKeys

Usage

Basic Usage

const obj = { a: 1, b: 2, c: 3 };
const keys = extractObjectKeys(obj); // Returns ['a', 'b', 'c']

With Tuple Return Type

const obj = { a: 1, b: 2, c: 3 };
const keys = extractObjectKeys(obj, true); // Returns ['a', 'b', 'c'] as Tuple

With Empty Object

TypeScript will complain and it will return empty array.

const keys = extractObjectKeys({}); // Returns []

With Null/Undefined

TypeScript will complain and it will return empty array.

const keys = extractObjectKeys(null); // Returns []
const keys = extractObjectKeys(undefined); // Returns []

API

Type Parameters

Parameter	Description
T	A generic object type

Parameters

Parameter	Type	Description
obj	T	The object to extract keys from
tuple	boolean	Optional. If true, returns keys as tuple instead of an array.

Return Value

• Without tuple: Array<keyof T> - An array of keys from the specified object
• With tuple: true: Tuple<keyof T> - A tuple of keys from the specified object
• Returns empty array/tuple if the object is null/undefined/empty

Examples

Simple Object

const user = {
  id: 1,
  name: 'John Doe',
  email: 'john@example.com'
};

const keys = extractObjectKeys(user); // ['id', 'name', 'email']

With Tuple

const user = {
  id: 1,
  name: 'John Doe',
  email: 'john@example.com'
};

const keys = extractObjectKeys(user, true); // ['id', 'name', 'email'] as Tuple

Nested Object

const product = {
  id: 1,
  name: 'Laptop',
  details: {
    brand: 'Dell',
    price: 999
  }
};

const keys = extractObjectKeys(product); // ['id', 'name', 'details']
// Note: Only top-level keys are returned

Edge Cases

TypeScript will complain and it will return empty array.

// Empty object
extractObjectKeys({}); // []

// Null case
extractObjectKeys(null); // []

// Undefined case
extractObjectKeys(undefined); // []

// Non-object values
extractObjectKeys('string'); // []
extractObjectKeys(123); // []

Notes

• This function only returns top-level (own) enumerable properties
• Returns an empty array for empty objects, null, undefined, or non-object values
• Internally uses Object.keys() with proper TypeScript typing
• Symbol-keyed properties are not included in the result
• Inherited properties are not included (only own properties)
• The return type is properly typed as Array<keyof T> for better TypeScript support
• For nested objects, only the top-level keys are extracted
• When using the tuple parameter, the order is determined by TypeScript's type system and may not match runtime order

---

extractObjectKeysDeep

Recursively extracts all nested keys from an object with proper typing.

Import

import { extractObjectKeysDeep } from 'nhb-toolbox';

Function Signatures

extractObjectKeysDeep<T extends GenericObject>(obj: T): Array<DeepKeys<T>>;

Aliases

• extractKeysDeep - Alias for extractObjectKeysDeep

Usage

Basic Usage

const obj = { 
  a: 1, 
  b: { 
    c: 2, 
    d: { 
      e: 3 
    } 
  } 
};
const keys = extractObjectKeysDeep(obj); 
// Returns ['a', 'b', 'c', 'd', 'e']

With Empty Object

const keys = extractObjectKeysDeep({}); // Returns []

With Null/Undefined

const keys = extractObjectKeysDeep(null); // Returns []
const keys = extractObjectKeysDeep(undefined); // Returns []

API

Type Parameters

Parameter	Description
T	A generic object type

Parameters

Parameter	Type	Description
obj	T	The object to extract keys from

Return Value

Array<DeepKeys<T>>: An array of all nested keys from the specified object, or empty array if the object is null/undefined/empty.

Examples

Simple Nested Object

const user = {
  id: 1,
  profile: {
    name: 'John Doe',
    address: {
      street: '123 Main St',
      city: 'New York'
    }
  }
};

const keys = extractObjectKeysDeep(user); 
// ['id', 'profile', 'name', 'address', 'street', 'city']

Complex Object

const company = {
  name: 'Tech Corp',
  departments: {
    engineering: {
      team: 'dev',
      lead: 'Alice'
    },
    sales: {
      region: 'north',
      manager: 'Bob'
    }
  }
};

const keys = extractObjectKeysDeep(company);
// ['name', 'departments', 'engineering', 'team', 'lead', 'sales', 'region', 'manager']

Edge Cases

// Empty object
extractObjectKeysDeep({}); // []

// Null case
extractObjectKeysDeep(null); // []

// Undefined case
extractObjectKeysDeep(undefined); // []

// Flat object (same as extractObjectKeys)
extractObjectKeysDeep({ a: 1, b: 2 }); // ['a', 'b']

Notes

• Recursively extracts all nested keys from an object
• Returns an empty array for empty objects, null, undefined, or non-object values
• For only top-level keys, use extractObjectKeys or its alias extractKeys
• The return type is properly typed as Array<DeepKeys<T>> for better TypeScript support
• Useful when you need to access all properties in a deeply nested object structure