From ae6fba94954bac6430902f77b0d1113a98a75b18 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Thu, 16 Nov 2023 17:02:17 +0800
Subject: [PATCH] perf: optimize makeMap

---
 packages/shared/src/makeMap.ts | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/packages/shared/src/makeMap.ts b/packages/shared/src/makeMap.ts
index b598704c673..9c4180c1e7a 100644
--- a/packages/shared/src/makeMap.ts
+++ b/packages/shared/src/makeMap.ts
@@ -9,10 +9,8 @@ export function makeMap(
   str: string,
   expectsLowerCase?: boolean
 ): (key: string) => boolean {
-  const map: Record<string, boolean> = Object.create(null)
-  const list: Array<string> = str.split(',')
-  for (let i = 0; i < list.length; i++) {
-    map[list[i]] = true
-  }
-  return expectsLowerCase ? val => !!map[val.toLowerCase()] : val => !!map[val]
+  const set = new Set(str.split(','))
+  return expectsLowerCase
+    ? val => set.has(val.toLowerCase())
+    : val => set.has(val)
 }