Interactive rating component

If a user doesn't choose any value 1-5 and still hits submit, is there a code to prevent them from doing so?

I tried to write javascript code where it would be impossible for a user to hit submit button if they don't choose any value 1 - 5 to give rating.

In that case, they wouldn't be able to proceed even if they pressed submit, because there would be an alert displayed, warning them to first choose a value between 1 and 5.

I know there should be an if statement and compare rating to the one we get from buttons as input, but I couldn't complete the code. The furthest I got was to be able to display this alert, but it was then displayed each time I pressed submit, instead of only when I didn't choose any value.