First of all, new line character depends on the OS: http://en.wikipedia.org/wiki/newline.
The code is unrelated to jQuery, but only related to JavaScript. It could be:
a = 13;
b = "some text";
c = a + "\n" + b;
d = a + "\r\n" + b;
Many modern components accept any consistent combinations of these characters, so it depends on how you use those strings.
Are you sure you really need it? More usually, JavaScript code produces strings for HTML rendering, which requires the
</br>
element.
—SA