IsLiteral: Don't restrict generic type (#684)

sindresorhus · Sep 30, 2023 · 4378507 · 4378507
1 parent 025f6e9
commit 4378507
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Showing 2 changed files with 22 additions and 2 deletions.
diff --git a/source/internal.d.ts b/source/internal.d.ts
@@ -261,3 +261,20 @@ export type IsNull<T> = [T] extends [null] ? true : false;
 Disallows any of the given keys.
 */
 export type RequireNone<KeysType extends PropertyKey> = Partial<Record<KeysType, never>>;
+
+/**
+Returns a boolean for whether the given type is primitive value or primitive type.
+
+@example
+```
+IsPrimitive<'string'>
+//=> true
+
+IsPrimitive<string>
+//=> true
+
+IsPrimitive<Object>
+//=> false
+```
+*/
+export type IsPrimitive<T> = [T] extends [Primitive] ? true : false;
diff --git a/source/is-literal.d.ts b/source/is-literal.d.ts
@@ -1,6 +1,6 @@
 import type {Primitive} from './primitive';
 import type {Numeric} from './numeric';
-import type {IsNotFalse} from './internal';
+import type {IsNotFalse, IsPrimitive} from './internal';
 import type {IsNever} from './is-never';
 
 /**
@@ -250,4 +250,7 @@ stripLeading(str, 'abc');
 @category Type Guard
 @category Utilities
 */
-export type IsLiteral<T extends Primitive> = IsNotFalse<IsLiteralUnion<T>>;
+export type IsLiteral<T> =
+	IsPrimitive<T> extends true
+		? IsNotFalse<IsLiteralUnion<T>>
+		: false;