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    toConstantCaseKeys es-toolkit

    Returns a new object with all keys in objects and arrays converted to CONSTANT_CASE.

    Constant case is a naming convention where each word in an identifier is written in uppercase and connected with underscores (_). For example, it's written as CONSTANT_CASE.

    const constantCased = toConstantCaseKeys(obj);

    Usage

    toConstantCaseKeys(obj)

    Use toConstantCaseKeys when you want to convert all keys of an object to CONSTANT_CASE. Nested objects and objects within arrays are also converted recursively.

    For example, object keys are converted as follows:

    • camelCase → CONSTANT_CASE (e.g. userId → USER_ID)
    • PascalCase → CONSTANT_CASE (e.g. UserId → USER_ID)
    • snake_case → CONSTANT_CASE (e.g. first_name → FIRST_NAME, last → LAST)
    import { toConstantCaseKeys } from 'es-toolkit/object';

// Basic object conversion
const obj = { userId: 1, firstName: 'John', lastName: 'Doe' };
const result = toConstantCaseKeys(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 = toConstantCaseKeys(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 = toConstantCaseKeys(nested);
// nestedResult is {
//   USER_DATA: {
//     USER_ID: 1,
//     CONTACT_INFO: {
//       EMAIL_ADDRESS: '[email protected]',
//       PHONE_NUMBER: '123-456-7890'
//     }
//   }
// }

    Parameters

    objTrequired

    The object, array, or primitive value to convert keys to CONSTANT_CASE.

    Returns

    Returns a new object with all keys converted to CONSTANT_CASE.

    ToConstantCaseKeys<T>
    Source: es-toolkit

    Re-exported verbatim from es-toolkit. Implementation, edge cases, and performance behavior are owned upstream. This page mirrors the documentation at the pinned version; the linked source is authoritative.