diff --git a/beli.js b/beli.js
index 060efcd..4699fc1 100644
--- a/beli.js
+++ b/beli.js
@@ -1,15 +1,20 @@
+"use strict"
 function beli(uang, obj, cb){
   console.log(`Saya pergi membeli ${obj.item}`)
-  setTimeout(function(){
-    let kembalian = uang - obj.harga
-    if (kembalian > 0) {
-      console.log(`Saya sudah membeli ${obj.item} uang kembaliannya ${kembalian}`);
-      cb(kembalian)
-    }else{
-      console.log(`uang gk cukup nih buat beli ${obj.item} kembaliannya cuma ${kembalian}`);
-      cb(0)
-    }
-  }, obj.waktu);
+  return new Promise(function(resolve, reject) {
+    setTimeout(function(){
+      let kembalian = uang - obj.harga
+      if (kembalian > 0) {
+        console.log(`Saya sudah membeli ${obj.item} uang kembaliannya ${kembalian}`);
+        resolve(kembalian)
+
+      }else{
+        console.log(`uang gk cukup nih buat beli ${obj.item} kembaliannya cuma ${kembalian}`);
+        reject(0)
+      }
+    }, obj.waktu);
+  });
 }
 
+
 module.exports = beli;
diff --git a/index.js b/index.js
index e69de29..5a25812 100644
--- a/index.js
+++ b/index.js
@@ -0,0 +1,50 @@
+"use strict"
+const beli=require('./beli.js')
+var uang=10000
+var obj=[{
+            item:'kopi',
+            harga: 2000,
+            waktu : 2000
+          },
+          {
+            item:'permen',
+            harga: 500,
+            waktu: 2000
+          },
+          {
+            item:'teh',
+            harga: 5000,
+            waktu: 2000
+          },
+          {
+            item:'ciki',
+            harga: 3500,
+            waktu: 2000
+          },
+          {
+            item:'kue',
+            harga: 1000,
+            waktu: 2000
+          }
+      ]
+
+beli(uang,obj[0]).then(sisa=>{
+  beli(sisa,obj[1]).then(sisa=>{
+    beli(sisa,obj[2]).then(sisa=>{
+      beli(sisa,obj[3]).then(sisa=>{
+        beli(sisa,obj[4]).then(sisa=>{
+        }).catch(err=>{
+          console.log(err);
+        })
+      }).catch(err=>{
+        console.log(err);
+      })
+    }).catch(err=>{
+      console.log(err);
+    })
+  }).catch(err=>{
+    console.log(err);
+  })
+}).catch(err=>{
+  console.log(err);
+})