@niche-works/types

@niche-works/types

@niche-works/types is a niche library of TypeScript utility types.

日本語のREADMEはこちら

Installation

npm install @niche-works/types

Type Reference

Value state types

Type	Definition	Description
Nullish	undefined | null	null or undefined
Empty	Nullish | ''	Nullish plus empty string
Falsy	Empty | false | 0 | -0 | 0n | NaN	All JavaScript falsy values

Record types

Generic record types whose keys are PropertyKey (string | number | symbol).

Type	Definition	Description
FlexibleRecord<V>	Record<PropertyKey, V>	Base type with a generic value type
LooseRecord	FlexibleRecord<any>	Flexibility-first type that accepts any value type
StrictRecord	FlexibleRecord<unknown>	Safety-first type that requires a type guard to use

Dictionary types

Record types whose keys are string only.

Type	Definition	Description
FlexibleDictionary<V>	Record<string, V>	Base type with a generic value type
LooseDictionary	FlexibleDictionary<any>	Flexibility-first type that accepts any value type
StrictDictionary	FlexibleDictionary<unknown>	Safety-first type that requires a type guard to use

Array types

Type	Definition	Description
LooseArray	any[]	Flexibility-first array type that accepts any element
StrictArray	unknown[]	Safety-first array type that requires a type guard to use

Synchronous function types

Type	Description
SyncFunction<P extends any[], R>	Base type with configurable parameter type P and return type R
SyncLooseFunction	Flexibility-first type with any parameters and return value
SyncStrictFunction	Safety-first type with never[] parameters and unknown return value

Asynchronous function types

Type	Description
AsyncFunction<P extends any[], R>	Base type with configurable parameter type P and return Promise<R>
AsyncLooseFunction	Flexibility-first type with any parameters and return value
AsyncStrictFunction	Safety-first type with never[] parameters and Promise<unknown> return value

Iteratee types

Type	Signature	Description
IndexedIteratee<V, R>	(value: V, index: number, data: V[]) => R	Callback for iterating over arrays
KeyedIteratee<V, R>	(value: V, key: PropertyKey, data: Record<PropertyKey, V>) => R	Callback for iterating over objects

Advanced utility types

Keys<RECORD, TYPE>

Generates a union type of the keys of a record. When TYPE is specified, only keys whose values extend that type are included.

import type { Keys } from '@niche-works/types';

type Props = {
  id: number;
  name: string;
  label: string;
  createdAt: Date;
};

// Union of all keys
type AllKeys = Keys<Props>;
// => 'id' | 'name' | 'label' | 'createdAt'

// Only keys whose value is string
type StringKeys = Keys<Props, string>;
// => 'name' | 'label'

Prefixed<PREFIX, RECORD, KEYS>

Generates a new type by prepending a camelCase prefix to the specified properties of a record.
When KEYS is omitted, all properties are targeted.

import type { Prefixed } from '@niche-works/types';

type Props = {
  width: number;
  height: number;
  color: string;
};

// Prefix all properties
type PrefixedProps = Prefixed<'default', Props>;
// => { defaultWidth: number; defaultHeight: number; defaultColor: string }

// Prefix only selected properties
type PartialPrefixedProps = Prefixed<'default', Props, 'width' | 'height'>;
// => { defaultWidth: number; defaultHeight: number; color: string }

PrefixedUnion<PREFIX, UNION, KEYS>

Generates a new union type by prepending a camelCase prefix to the members of a union.
When KEYS is omitted, all members are targeted.

import type { PrefixedUnion } from '@niche-works/types';

type Direction = 'top' | 'right' | 'bottom' | 'left';

// Prefix all members
type PaddingKeys = PrefixedUnion<'padding', Direction>;
// => 'paddingTop' | 'paddingRight' | 'paddingBottom' | 'paddingLeft'

// Prefix only selected members
type PartialMarginKeys = PrefixedUnion<'margin', Direction, 'top' | 'bottom'>;
// => 'marginTop' | 'right' | 'marginBottom' | 'left'

License

MIT