Remove line breaks if there are no characters on that line

Question

I'm trying to remove linebreaks if there are no characters next to it.

I'd like to keep Line1, Line2, Line3 untouched but the break after Line3 and before Line1 removed.

I tried:

Element.value = Element.value.replace(/\n?![A-z]/g, "");

I'm not too good with regex.

Thanks.

Answer 1

.replace(/(\r?\n){2,}/g, '\n').replace(/^\r?\n|\r?\n$/g, '');

Demo

This regex replaces sequences of 2 or more line breaks with a single line break, then remove leading and trailing line breaks.