Try this:
if(Math.floor(id) == id && $.isNumeric(id))
alert('yes its an int!');
$.isNumeric(id)
checks whether it’s numeric or not
Math.floor(id) == id
will then determine if it’s really in integer value and not a float. If it’s a float parsing it to int will give a different result than the original value. If it’s int both will be the same.