Type Alias ListLikeIndex<L>

ListLikeIndex: L extends Record<infer K, any>
? K
: L extends Map<infer MK, any> ? MK : string | number

Extract the key or index type from a keyed list-like structure.

Type Parameters

L
List-like type

Remarks

For arrays and other non-keyed collections, this defaults to string | number.

Example

type I1 = ListLikeIndex< Record< string, number > >; // string
type I2 = ListLikeIndex< Map< number, string > >;    // number
type I3 = ListLikeIndex< number[] >;                 // string | number