diff --git a/playground/5-es6-objects.js b/playground/5-es6-objects.js
index c792f6d..c65a3ea 100644
--- a/playground/5-es6-objects.js
+++ b/playground/5-es6-objects.js
@@ -29,7 +29,7 @@ const product = {
 // console.log(stock)
 // console.log(rating)
 
-const transaction = (type, {label, stock}) => {
+const transaction = (type, { label, stock = 0 } = {}) => {
   console.log(type, label, stock)
 }
 
diff --git a/playground/7-default-params.js b/playground/7-default-params.js
new file mode 100644
index 0000000..c8e76b5
--- /dev/null
+++ b/playground/7-default-params.js
@@ -0,0 +1,7 @@
+const greeter = (name = 'user', age) => {
+  console.log('Hello ' + name)
+}
+
+greeter('Jason')
+
+greeter()
diff --git a/web-server/src/app.js b/web-server/src/app.js
index 1d103e9..f7549e1 100644
--- a/web-server/src/app.js
+++ b/web-server/src/app.js
@@ -48,7 +48,7 @@ app.get('/weather', (req, res) => {
     })
   }
 
-  geocode(req.query.address, (error, {latitude, longitude, location}) => {
+  geocode(req.query.address, (error, {latitude, longitude, location} = {}) => {
     if (error) {
       return res.send({ error: error })
     }