@xylabs/enum

@xylabs/enum

Base functionality used throughout XY Labs TypeScript/JavaScript libraries

Reference

@xylabs/enum

Type Aliases

• Enum
• EnumKey
• EnumValue

Functions

• Enum

functions

Enum

@xylabs/enum

function Enum<T>(obj): Enum<T>;

Transforms a given record object into a readonly "enum-like" structure while preserving the literal types of its values. This allows you to use the returned object both at runtime (for lookups) and at compile time (for strongly typed values).

To maintain literal types (i.e., prevent them from being widened to string, number, etc.), ensure you annotate your object with as const before passing it to Enum.

Type Parameters

T

T extends Record<string | number | symbol, unknown>

A record type with string keys and any kind of values.

Parameters

obj

Readonly<T>

A readonly record object annotated with as const.

Returns

Enum<T>

A readonly version of the provided record, preserving exact literal value types.

Example

// Defining a record with literal types using as const:
const DnsRecordType = Enum({
  A: 1,
  AAAA: 28,
  CAA: 257,
  CNAME: 5,
  DNAME: 39,
  MX: 15,
  NS: 2,
  PTR: 12,
  SOA: 6,
  SPF: 99,
  SRV: 33,
  TXT: 16,
} as const);

// DnsRecordType is now a readonly object:
// {
//   readonly A: 1;
//   readonly AAAA: 28;
//   readonly CAA: 257;
//   readonly CNAME: 5;
//   readonly DNAME: 39;
//   readonly MX: 15;
//   readonly NS: 2;
//   readonly PTR: 12;
//   readonly SOA: 6;
//   readonly SPF: 99;
//   readonly SRV: 33;
//   readonly TXT: 16;
// }

type-aliases

Enum

@xylabs/enum

type Enum<T> = { readonly [K in keyof T]: T[K] };

A utility type that, given a Record<string, unknown>, returns a readonly version of that record. This results in a type where all properties of T are readonly.

Type Parameters

T

T extends Readonly<Record<string | number | symbol, unknown>>

The record type to make readonly.

Example

// Given a record:
export const DnsRecordType = Enum({
  A: 1,
  AAAA: 28,
  CAA: 257,
  CNAME: 5,
  DNAME: 39,
  MX: 15,
  NS: 2,
  PTR: 12,
  SOA: 6,
  SPF: 99,
  SRV: 33,
  TXT: 16,
})

// Now the type inference will preserve the literal types:
export type DnsRecordType = Enum<typeof DnsRecordType>

EnumKey

@xylabs/enum

type EnumKey<T, K> = keyof K;

A utility type that, given an Enum object, returns the union of its keys.

Type Parameters

T

T extends Record<string | number | symbol, unknown>

K

K = Enum<T>

EnumValue

@xylabs/enum

type EnumValue<T, K> = K[keyof K];

A utility type that, given an Enum object, returns the union of its values.

Type Parameters

T

T extends Record<string | number | symbol, unknown>

K

K = Enum<T>

Part of sdk-js

Maintainers

• Arie Trouw (arietrouw.com)
• Matt Jones
• Joel Carter
• Jordan Trouw

License

See the LICENSE file for license details

Credits

Made with 🔥 and ❄️ by XYLabs