Cancel dragging of a sortable item

Question

An absolutely common sortable case:

  
Item         


        

Answer 1

Try this example

$('#list1').sortable({
    connectWith: 'ul'
});    

$('#list2').sortable({
    connectWith: 'ul',
    receive: function(ev, ui) {
       if(ui.item.hasClass("number"))
          ui.sender.sortable("cancel");
    }
});