docs/reference/object/toSnakeCaseKeys.md
Returns a new object with all keys in objects and arrays converted to snake_case.
Snake case is a naming convention where each word in an identifier is written in lowercase and connected with underscores (_). For example, it's written as snake_case.
const snakeCased = toSnakeCaseKeys(obj);
toSnakeCaseKeys(obj)Use toSnakeCaseKeys when you want to convert all keys of an object to snake_case. Nested objects and objects within arrays are also converted recursively.
For example, object keys are converted as follows:
camelCase → snake_case (e.g. userId → user_id)PascalCase → snake_case (e.g. UserId → user_id)UPPERCASE_KEYS → snake_case (e.g. FIRST_NAME → first_name, LAST → last)import { toSnakeCaseKeys } from 'es-toolkit/object';
// Basic object conversion
const obj = { userId: 1, firstName: 'John', lastName: 'Doe' };
const result = toSnakeCaseKeys(obj);
// result is { user_id: 1, first_name: 'John', last_name: 'Doe' }
// Objects within arrays are also converted
const users = [
{ userId: 1, firstName: 'John' },
{ userId: 2, firstName: 'Jane' },
];
const convertedUsers = toSnakeCaseKeys(users);
// convertedUsers is [{ user_id: 1, first_name: 'John' }, { user_id: 2, first_name: 'Jane' }]
// Nested objects are fully converted
const nested = {
userData: {
userId: 1,
contactInfo: {
emailAddress: '[email protected]',
phoneNumber: '123-456-7890',
},
},
};
const nestedResult = toSnakeCaseKeys(nested);
// nestedResult is {
// user_data: {
// user_id: 1,
// contact_info: {
// email_address: '[email protected]',
// phone_number: '123-456-7890'
// }
// }
// }
obj (T): The object, array, or primitive value to convert keys to snake_case.(ToSnakeCaseKeys<T>): Returns a new object with all keys converted to snake_case.