J.S. how to avoid ' undefined ' on switch?

Question

This code is supposed to display summer when it is summer, fall when it's fall, winter when It's...

But right now It's summer, and It displays undefined for the other seasons.
Is there a way to secure that '(avoid undefined)?

Answer 1

https://code.sololearn.com/WFvNJfrcG9Np/?ref=app

Answer 2

default:

Answer 3

use default to set a value if all case values are not the input value