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 = $("#ipadmenu section.current").data('order') - 1; and gives me -1.
Thank you for your help.
+ serves two purposes. It adds in the case of numbers and concatenates in the case of strings. You can fix this by casting the string as a number with this:
var previousmenu = Number($("#ipadmenu section.current").data('order')) + 1;
If one the variables you are 'adding' is a string, javascript decides that what you really wanted to do was concatenate the string and the number together (hence "0" + 1 = "01");
What you need to do is something like..
var order = parseInt($("#ipadmenu section.current").data('order'), 10);
order = order + 1;
Because it's a string, not an integer, thus doing string concatenation... aaand welcome to the whacky world of JavaScript, because you guessed it, "0" - 1 will return a number.
In any case, use parseInt(...) or + $("blah").data('order') + 1 and you'll be happier, if not confused.
