diff --git a/js/spec/gilded_rose_spec.js b/js/spec/gilded_rose_spec.js
index 44c3838b..1d9c7502 100644
--- a/js/spec/gilded_rose_spec.js
+++ b/js/spec/gilded_rose_spec.js
@@ -1,9 +1,98 @@
-describe("Gilded Rose", function() {
-
-  it("should foo", function() {
-    const gildedRose = new Shop([ new Item("foo", 0, 0) ]);
+describe('Gilded Rose', function() {
+  it('should foo', function() {
+    const gildedRose = new Shop([new Item('foo', 0, 0)]);
     const items = gildedRose.updateQuality();
-    expect(items[0].name).toEqual("fixme");
+    expect(items[0].name).toEqual('foo');
   });
 
+  it('can updateQuality for Backstage Passes', () => {
+    const gildedRose = new Shop([
+      new Item('Backstage passes to a TAFKAL80ETC concert', 15, 20),
+      new Item('Backstage passes to a TAFKAL80ETC concert', 10, 46),
+      new Item('Backstage passes to a TAFKAL80ETC concert', 5, 49)
+    ]);
+    const items = gildedRose.updateQuality();
+    expect(items[0].name).toEqual('Backstage passes to a TAFKAL80ETC concert');
+    expect(items[0].sellIn).toEqual(14);
+    expect(items[0].quality).toEqual(21);
+
+    expect(items[1].name).toEqual('Backstage passes to a TAFKAL80ETC concert');
+    expect(items[1].sellIn).toEqual(9);
+    expect(items[1].quality).toEqual(48);
+
+    expect(items[2].name).toEqual('Backstage passes to a TAFKAL80ETC concert');
+    expect(items[2].sellIn).toEqual(4);
+    expect(items[2].quality).toEqual(50);
+  });
+
+  it('can updateQuality for Aged Brie', () => {
+    const gildedRose = new Shop([new Item('Aged Brie', 2, 0)]);
+    const items = gildedRose.updateQuality();
+    expect(items[0].name).toEqual('Aged Brie');
+    expect(items[0].sellIn).toEqual(1);
+    expect(items[0].quality).toEqual(1);
+  });
+
+  it('can updateQuality for Sulfuras', () => {
+    const gildedRose = new Shop([
+      new Item('Sulfuras, Hand of Ragnaros', 0, 80),
+      new Item('Sulfuras, Hand of Ragnaros', -1, 80)
+    ]);
+    const items = gildedRose.updateQuality();
+    expect(items[0].name).toEqual('Sulfuras, Hand of Ragnaros');
+    expect(items[0].sellIn).toEqual(-1);
+    expect(items[0].quality).toEqual(80);
+
+    expect(items[1].name).toEqual('Sulfuras, Hand of Ragnaros');
+    expect(items[1].sellIn).toEqual(-2);
+    expect(items[1].quality).toEqual(80);
+  });
+
+  it('can updateQuality for basic items', () => {
+    const gildedRose = new Shop([
+      new Item('+5 Dexterity Vest', 10, 20),
+      new Item('Elixir of the Mongoose', 5, 7)
+    ]);
+
+    const items = gildedRose.updateQuality();
+    expect(items[0].name).toEqual('+5 Dexterity Vest');
+    expect(items[0].sellIn).toEqual(9);
+    expect(items[0].quality).toEqual(19);
+
+    expect(items[1].name).toEqual('Elixir of the Mongoose');
+    expect(items[1].sellIn).toEqual(4);
+    expect(items[1].quality).toEqual(6);
+  });
+
+  it('can updateQuality for conjured items', () => {
+    const gildedRose = new Shop([new Item('Conjured Mana Cake', 3, 6)]);
+    const items = gildedRose.updateQuality();
+    expect(items[0].sellIn).toEqual(2);
+    expect(items[0].quality).toEqual(4);
+  });
+
+  it('Once the sell by date has passed, Quality degrades twice as fast', () => {
+    const gildedRose = new Shop([new Item('+5 Dexterity Vest', -2, 20)]);
+
+    const items = gildedRose.updateQuality();
+    expect(items[0].sellIn).toEqual(-3);
+    expect(items[0].quality).toEqual(18);
+  });
+
+  it('The Quality of an item is never negative', () => {
+    const gildedRose = new Shop([new Item('+5 Dexterity Vest', -2, 1)]);
+
+    const items = gildedRose.updateQuality();
+    expect(items[0].name).toEqual('+5 Dexterity Vest');
+    expect(items[0].sellIn).toEqual(-3);
+    expect(items[0].quality).toEqual(0);
+  });
+
+  it('will not increase quality over 50', () => {
+    const gildedRose = new Shop([new Item('Aged Brie', -1, 50)]);
+    const items = gildedRose.updateQuality();
+    expect(items[0].name).toEqual('Aged Brie');
+    expect(items[0].sellIn).toEqual(-2);
+    expect(items[0].quality).toEqual(50);
+  });
 });
diff --git a/js/src/gilded_rose.js b/js/src/gilded_rose.js
index 5358125e..ce27e06b 100644
--- a/js/src/gilded_rose.js
+++ b/js/src/gilded_rose.js
@@ -1,5 +1,5 @@
 class Item {
-  constructor(name, sellIn, quality){
+  constructor(name, sellIn, quality) {
     this.name = name;
     this.sellIn = sellIn;
     this.quality = quality;
@@ -7,56 +7,55 @@ class Item {
 }
 
 class Shop {
-  constructor(items=[]){
+  constructor(items = []) {
     this.items = items;
   }
-  updateQuality() {
-    for (var i = 0; i < this.items.length; i++) {
-      if (this.items[i].name != 'Aged Brie' && this.items[i].name != 'Backstage passes to a TAFKAL80ETC concert') {
-        if (this.items[i].quality > 0) {
-          if (this.items[i].name != 'Sulfuras, Hand of Ragnaros') {
-            this.items[i].quality = this.items[i].quality - 1;
-          }
-        }
+  increaseQuality(item) {
+    if (item.quality < 50) {
+      item.quality++;
+    }
+    return item;
+  }
+  decreaseQuality(item) {
+    if (item.quality > 0) {
+      if (item.sellIn < 0 || item.name === 'Conjured Mana Cake') {
+        item.quality = item.quality - 2 > 0 ? item.quality - 2 : 0;
       } else {
-        if (this.items[i].quality < 50) {
-          this.items[i].quality = this.items[i].quality + 1;
-          if (this.items[i].name == 'Backstage passes to a TAFKAL80ETC concert') {
-            if (this.items[i].sellIn < 11) {
-              if (this.items[i].quality < 50) {
-                this.items[i].quality = this.items[i].quality + 1;
-              }
-            }
-            if (this.items[i].sellIn < 6) {
-              if (this.items[i].quality < 50) {
-                this.items[i].quality = this.items[i].quality + 1;
-              }
-            }
-          }
-        }
-      }
-      if (this.items[i].name != 'Sulfuras, Hand of Ragnaros') {
-        this.items[i].sellIn = this.items[i].sellIn - 1;
-      }
-      if (this.items[i].sellIn < 0) {
-        if (this.items[i].name != 'Aged Brie') {
-          if (this.items[i].name != 'Backstage passes to a TAFKAL80ETC concert') {
-            if (this.items[i].quality > 0) {
-              if (this.items[i].name != 'Sulfuras, Hand of Ragnaros') {
-                this.items[i].quality = this.items[i].quality - 1;
-              }
-            }
-          } else {
-            this.items[i].quality = this.items[i].quality - this.items[i].quality;
-          }
-        } else {
-          if (this.items[i].quality < 50) {
-            this.items[i].quality = this.items[i].quality + 1;
-          }
-        }
+        item.quality--;
       }
     }
+    return item;
+  }
+  updateQuality() {
+    this.items.map(item => {
+      switch (item.name) {
+        case 'Aged Brie':
+          this.increaseQuality(item);
+          item.sellIn--;
+          break;
+        case 'Backstage passes to a TAFKAL80ETC concert':
+          if (item.sellIn > 0) {
+            this.increaseQuality(item);
+            if (item.sellIn < 11) {
+              this.increaseQuality(item);
+            }
+            if (item.sellIn < 6) {
+              this.increaseQuality(item);
+            }
+          } else {
+            item.quality = 0;
+          }
+          item.sellIn--;
+          break;
+        case 'Sulfuras, Hand of Ragnaros':
+          item.sellIn--;
+          break;
 
+        default:
+          this.decreaseQuality(item);
+          item.sellIn--;
+      }
+    });
     return this.items;
   }
 }