jQuery从其他DropDown删除A DropDown中的选定选项，停止工作并挂起

Question

I am using the following javascript to remove a option selected in DropDown A , from DropDown B.

$('#A').bind('keypress', function(e){ 

      if ( e.which == 52 ){
        var selectedItems  = $('#A').val();
        var $list = $("#B"),
            toRemove = $(),
            selectedItems = $("#A").val();
        for ( var i = 0 ; i < selectedItems.length; i++) {
          toRemove = toRemove.add($list.find('option[value="' + selectedItems[i] + '"]'));
        }
        toRemove.remove();
      }
});

The option is removed from DropDown B , but , the javascript hangs out when I press the key. Please help.

Is there some other jquery ?

Answer 1

I can't explain why everything is hanging, but I think there are some things that could be improved in your code.

If you have a "dropdown" then the select element will be single-select, which means the .val() method will be returning a string rather than an array (it only returns an array in the case of a <select multiple="multiple"> element), and if it's returning a string you don't need the for loop because - well, there's nothing to loop through. If that is true the simplified version of your code would be this:

$('#A').bind('keypress', function(e){
    if ( e.which === 52 ){
       $('#B option[value="' + $(this).val() + '"]').remove();
    }
});

If there is no matching option in #B for the selected item then nothing will happen.

I don't understand the significance of key code 52, but I've left that in.