From c408f5a2680b750c8a000289954dacc2296acc00 Mon Sep 17 00:00:00 2001
From: Filip Skokan <panva.ip@gmail.com>
Date: Thu, 9 Jun 2022 19:05:31 +0200
Subject: [PATCH] Fix `NaN` detection in `.is()` (#159)

---
 source/index.ts | 3 ++-
 test/test.ts    | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/source/index.ts b/source/index.ts
index 5ce333d..39e5883 100644
--- a/source/index.ts
+++ b/source/index.ts
@@ -51,6 +51,7 @@ const objectTypeNames = [
 	'FormData',
 	'URLSearchParams',
 	'HTMLElement',
+	'NaN',
 	...typedArrayTypeNames
 ] as const;
 
@@ -111,7 +112,7 @@ function is(value: unknown): TypeName {
 		case 'string':
 			return 'string';
 		case 'number':
-			return 'number';
+			return Number.isNaN(value) ? 'NaN' : 'number';
 		case 'boolean':
 			return 'boolean';
 		case 'function':
diff --git a/test/test.ts b/test/test.ts
index 71a4a9d..f4fe213 100644
--- a/test/test.ts
+++ b/test/test.ts
@@ -454,7 +454,7 @@ const types = new Map<string, Test>([
 			NaN,
 			Number.NaN
 		],
-		typename: 'number',
+		typename: 'NaN',
 		typeDescription: AssertionTypeDescription.nan
 	}],
 	['nullOrUndefined', {