To get the number you can try with the following regex
var cl = orderClass.prop('class').split(/\s+/); //split the classes to get an array
var clNumber = $.each( cl, function(index, val){ //iterate over ir
if (val.indexOf('order-') !== -1) { //find the match
return val.replace( /^\D+/g, '') // return back the number
}
});