I don't understand how Java script work with html.please explain it to me😐

Question

I already know some JavaScript and I decided to type it in JS section of code playground but it doesn't work why? What am I doing wrong?please help me to correct my mistake🙏

Answer 1

Include this following clause in the head tag:
<script src="Address/to/script.js"></script>

You can also leave CDN links there too.

Answer 2

Thank you so much ☺