From 47fc84784517622be4797be03b79b9c0b22666f1 Mon Sep 17 00:00:00 2001
From: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
Date: Sun, 19 Mar 2023 21:31:49 -0700
Subject: [PATCH] Potentially speed up / lower memory use of getTypeListId

---
 src/compiler/checker.ts | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index b975b9848853d..fbdac2eae1542 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -15081,7 +15081,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
     }
 
     function getTypeListId(types: readonly Type[] | undefined) {
-        let result = "";
+        let result: string[] | undefined;
         if (types) {
             const length = types.length;
             let i = 0;
@@ -15091,17 +15091,16 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 while (i + count < length && types[i + count].id === startId + count) {
                     count++;
                 }
-                if (result.length) {
-                    result += ",";
+                if (count === 1) {
+                    result = append(result, `${startId}`);
                 }
-                result += startId;
-                if (count > 1) {
-                    result += ":" + count;
+                else {
+                    result = append(result, `${startId}:${count}`);
                 }
                 i += count;
             }
         }
-        return result;
+        return result ? result.join(",") : "";
     }
 
     function getAliasId(aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) {