TupleToUnion: Support arrays (#504)

sindresorhus · Nov 5, 2022 · a68f6b2 · a68f6b2
1 parent e11ab80
commit a68f6b2
Show file tree

Hide file tree

Showing 2 changed files with 10 additions and 1 deletion.
diff --git a/source/tuple-to-union.d.ts b/source/tuple-to-union.d.ts
@@ -48,4 +48,4 @@ type NumberBool = typeof numberBool[number];
 
 @category Array
 */
-export type TupleToUnion<ArrayType> = ArrayType extends readonly [infer Head, ...(infer Rest)] ? Head | TupleToUnion<Rest> : never;
+export type TupleToUnion<ArrayType> = ArrayType extends readonly unknown[] ? ArrayType[number] : never;
diff --git a/test-d/tuple-to-union.ts b/test-d/tuple-to-union.ts
@@ -24,3 +24,12 @@ expectType<'c'>(c);
 
 declare const notAnArray: TupleToUnion<[]>;
 expectType<never>(notAnArray);
+
+declare const worksWithArrays: TupleToUnion<Array<string | number>>;
+expectType<string | number>(worksWithArrays);
+
+declare const resolvesToNeverForNonArrays: TupleToUnion<string | number>;
+expectType<never>(resolvesToNeverForNonArrays);
+
+declare const infiniteRestArgs: TupleToUnion<[string, ...number[]]>;
+expectType<string | number>(infiniteRestArgs);