WikaSilo

beli.js

@@ -1,15 +1,17 @@
-function beli(uang, obj, cb){
+function beli(uang, obj) {
   console.log(`Saya pergi membeli ${obj.item}`)
-  setTimeout(function(){
+  return new Promise((resolve, reject) =>{
     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)
+    if (kembalian >= 0) {
+      setTimeout(function(){
+        console.log(`Saya sudah membeli ${obj.item} uang kembaliannya ${kembalian}`)
+        resolve(kembalian)
+      }, obj.waktu)
+    } else {
+      console.log(`uang gk cukup nih buat beli ${obj.item}, cuma ada ${uang}`);
+      reject(uang)
     }
-  }, obj.waktu);
+  })
 }
 
 module.exports = beli;

index.js

@@ -0,0 +1,53 @@
+const beli = require('./beli.js')
+
+let uang = 7000
+
+let buku = {}
+buku.item = 'Buku'
+buku.harga = 2000
+buku.waktu = 1000
+
+let pulpen = {}
+pulpen.item = 'Pulpen'
+pulpen.harga = 1000
+pulpen.waktu = 1500
+
+let makanan = {}
+makanan.item = 'Makanan'
+makanan.harga = 5000
+makanan.waktu = 2000
+
+let minuman = {}
+minuman.item = 'Minuman'
+minuman.harga = 4000
+minuman.waktu = 2000
+
+let susu = {}
+susu.item = 'Susu'
+susu.harga = 7000
+susu.waktu = 2000
+
+beli(uang, buku)
+  .then(function (kembalian) {
+  return beli(kembalian, pulpen)
+  }).then(function (kembalian) {
+  return beli(kembalian, makanan)
+  }).then(function (kembalian) {
+  return beli(kembalian, minuman)
+  }).then(function (kembalian) {
+  return beli(kembalian, susu)
+  }).catch(reject =>{})      
+
+// beli(uang, buku)
+//   .then(function (kembalian) {
+//     beli(kembalian, pulpen)
+//     .then(function (kembalian) {
+//       beli(kembalian, makanan)
+//       .then(function (kembalian) {
+//         beli(kembalian, minuman)
+//         .then(function (kembalian) {
+//           beli(kembalian, susu)
+//         }).catch(reject =>{})
+//       }).catch(reject =>{})
+//     }).catch(reject =>{})
+//   }).catch(reject =>{})