diff --git a/src/pages/playground/app.vue b/src/pages/playground/app.vue
index aa0fa67..7ed4518 100644
--- a/src/pages/playground/app.vue
+++ b/src/pages/playground/app.vue
@@ -55,9 +55,9 @@ export default {
           } catch (e) {}
         }
 
-        this.html = code.html
-        this.js = code.js
-        this.css = code.css
+        this.html = code.html || ''
+        this.js = code.js || ''
+        this.css = code.css || ''
         this.updatePreview()
       }
       this.$needUpdate = true