diff --git a/TypeScript/app/gilded-rose.ts b/TypeScript/app/gilded-rose.ts
index 5280de88..99501650 100644
--- a/TypeScript/app/gilded-rose.ts
+++ b/TypeScript/app/gilded-rose.ts
@@ -18,18 +18,20 @@ export class GildedRose {
   }
 
   updateQuality() {
-    this.items.forEach((item, i) => {
-      item.quality = updateItemQuality(item)
-    })
+    this.items = this.items.map((item) => ({
+      ...item,
+      quality: updateItemQuality(item)
+    }))
 
+    this.items = this.items.map((item) => ({
+      ...item,
+      sellIn: updateItemSellIn(item)
+    }))
 
-    this.items.forEach((item, i) => {
-      item.sellIn = updateItemSellIn(item)
-    })
-
-    this.items.forEach((item, i) => {
-      item.quality = sellInBelow0(item)
-    })
+    this.items = this.items.map(item => ({
+      ...item,
+      quality: sellInBelow0(item)
+    }))
     return this.items;
   }
 }