import type { ArrayEntry, MapEntry, ObjectEntry, SetEntry } from "./entry"; | |
type ArrayEntries<BaseType extends readonly unknown[]> = Array<ArrayEntry<BaseType>>; | |
type MapEntries<BaseType> = Array<MapEntry<BaseType>>; | |
type ObjectEntries<BaseType> = Array<ObjectEntry<BaseType>>; | |
type SetEntries<BaseType extends Set<unknown>> = Array<SetEntry<BaseType>>; | |
/** | |
Many collections have an `entries` method which returns an array of a given object's own enumerable string-keyed property [key, value] pairs. The `Entries` type will return the type of that collection's entries. | |
For example the {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/entries|`Object`}, {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/entries|`Map`}, {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/entries|`Array`}, and {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set/entries|`Set`} collections all have this method. Note that `WeakMap` and `WeakSet` do not have this method since their entries are not enumerable. | |
@see `Entry` if you want to just access the type of a single entry. | |
@example | |
``` | |
import type {Entries} from 'type-fest'; | |
interface Example { | |
someKey: number; | |
} | |
const manipulatesEntries = (examples: Entries<Example>) => examples.map(example => [ | |
// Does some arbitrary processing on the key (with type information available) | |
example[0].toUpperCase(), | |
// Does some arbitrary processing on the value (with type information available) | |
example[1].toFixed() | |
]); | |
const example: Example = {someKey: 1}; | |
const entries = Object.entries(example) as Entries<Example>; | |
const output = manipulatesEntries(entries); | |
// Objects | |
const objectExample = {a: 1}; | |
const objectEntries: Entries<typeof objectExample> = [['a', 1]]; | |
// Arrays | |
const arrayExample = ['a', 1]; | |
const arrayEntries: Entries<typeof arrayExample> = [[0, 'a'], [1, 1]]; | |
// Maps | |
const mapExample = new Map([['a', 1]]); | |
const mapEntries: Entries<typeof map> = [['a', 1]]; | |
// Sets | |
const setExample = new Set(['a', 1]); | |
const setEntries: Entries<typeof setExample> = [['a', 'a'], [1, 1]]; | |
``` | |
@category Object | |
@category Map | |
@category Set | |
@category Array | |
*/ | |
export type Entries<BaseType> = BaseType extends Map<unknown, unknown> | |
? MapEntries<BaseType> | |
: BaseType extends Set<unknown> | |
? SetEntries<BaseType> | |
: BaseType extends readonly unknown[] | |
? ArrayEntries<BaseType> | |
: BaseType extends object | |
? ObjectEntries<BaseType> | |
: never; | |