I'm trying to find the right regular expression for a number with a line skip at the end (
var rExp1 = /^\d+(\n)$/;
var aChamps = document.querySelector("textarea").value;
If you want to check for any line containing only a number on it, you can use:
If you just want to check that there's only a number, and then a newline, and nothing else:
(which is what you were checking for, but that's an odd input pattern.)
If you want to make sure textarea ONLY has lines that are numbers, it might be simpler to check that
string.replace(/[0-9\r\n]/g, '') == ''. This will confirm if it contains only numbers and newlines.