What is the error in this?

#1
#2

Here is the correct code: https://onecompiler.com/javascript/3wqtjz7jx

#3

what was the mistake?
and what is module?

#4

You did not use the lambda function in the callback function.
You can separate code/scripts in different modules and use them or import them in other files. This helps a lot if you have to use the same set of code in different files:
You can refer to this for more info: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules