Can be useful sometimes to find the index of a type in a readonly array (tuple), IE:
type Tuple = [T1, T2, T3];
type Index = IndexOf<Tuple, T1> // '0';This works:
export type Indexes<V extends readonly any[]> = {
[K in Exclude<keyof V, keyof Array<any>>]: K;
};
export type IndexOf<V extends readonly any[], T> = {
[I in keyof Indexes<V>]: V[I] extends T
? T extends V[I]
? I
: never
: never;
}[keyof Indexes<V>];It's possible to do some cool stuff with this
sindresorhus / type-fest
A collection of essential TypeScript types
14.2k
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