Added to one line. Print event

app.py

@@ -7,11 +7,7 @@ class State:
 
 state = State()
 
-js = """
-window.onMessage = (event) => {
-  alert('test')
-}
-"""
+window.onMessage = event => alert('Test message received: ' + event.data)
 
 def update_values(context, question):
     output = context + "\n" + question