Question

in this var: var previousmenu = $("#ipadmenu section.current").data('order') + 1;, this expression $("#ipadmenu section.current").data('order') equals 0.

Unfortunately the result of this is 01 and not 1. Why is this?

This for example seems to work:
var previousmenu = $("#ipadmenu section.current").data('order') - 1; and gives me -1.

Thank you for your help.

Answer 1

+ serves two purposes. It adds in the case of numbers and concatenates in the case of strings. You can fix this by casting the string as a number with this:

var previousmenu = Number($("#ipadmenu section.current").data('order')) + 1;