From be5680c087e2663b31767bcb38efdf75731a1533 Mon Sep 17 00:00:00 2001
From: YanagiEiichi <admin@web-tinker.com>
Date: Fri, 10 Apr 2020 22:13:48 +0800
Subject: [PATCH] narrowing return type of "array.includes"

---
 lib/lib.es2016.array.include.d.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/lib.es2016.array.include.d.ts b/lib/lib.es2016.array.include.d.ts
index 6bc6ef30e7e42..f40ddb487f5c1 100644
--- a/lib/lib.es2016.array.include.d.ts
+++ b/lib/lib.es2016.array.include.d.ts
@@ -25,6 +25,7 @@ interface Array<T> {
      * @param fromIndex The position in this array at which to begin searching for searchElement.
      */
     includes(searchElement: T, fromIndex?: number): boolean;
+    includes(searchElement: T, fromIndex?: number): searchElement is T;
 }
 
 interface ReadonlyArray<T> {
@@ -34,6 +35,7 @@ interface ReadonlyArray<T> {
      * @param fromIndex The position in this array at which to begin searching for searchElement.
      */
     includes(searchElement: T, fromIndex?: number): boolean;
+    includes(searchElement: T, fromIndex?: number): searchElement is T;
 }
 
 interface Int8Array {