下载asp.net中的验证

Question

我有两个相同项目的下拉菜单。如果在第一个下拉列表中选择了一个项目，则它不应出现在下一个下拉列表中。

Answer 1

Working Demo

$(function () {

  var lastRemovedIndex = -1;
  var lastRemovedOptionHtml = null;


  $('#ddl1').change(function () {

   if (lastRemovedIndex == -1) 
   {
     //both must have equal(and non-zero) number of children
     if ($(this).children().length < 1 || $(this).children().length != $('#ddl2').children().length)
        return;        
     else 
     {
        //if a has n children then b must have n-1 as 1 child was removed from b
        if ($(this).children().length - 1 != $('#ddl2').children().length)
            return;

  //Little complex. It says add the last removed option at its last position
        if (lastRemovedIndex != $('#ddl2').children().length)
            $('#ddl2').children().eq(lastRemovedIndex).before($(lastRemovedOptionHtml));
        else
            $('#ddl2').append(lastRemovedOptionHtml);
    }
    var objectToBeRemoved = $('#ddl2').children().eq(this.selectedIndex);
    lastRemovedIndex = objectToBeRemoved.index();
    lastRemovedOptionHtml = objectToBeRemoved[0].outerHTML;
    objectToBeRemoved.remove();
  });


});