剑道UI [下拉列表] - 多个元素中的冲突

3 个下拉列表都呈现了.k-list-scroller和.k-list-filter，但是如果您只需要访问当前下拉列表的这些元素，请在事件中使用this关键字keyup：

$(".k-list-filter input").keyup(function () {
    //"this" represents html input element
    var listFilter = $(this).closest('.k-list-filter');
    var listScroller = $(this).closest('.k-list-container').find('.k-list-scroller');
    // wait for Kendo to catch up
    delay(function () {
      // check the number of items in the list and make sure we don't already have an add link
        if (listScroller.find('ul > li').length === 0 && !listFilter.find(".newItem").length) {
            listFilter.find('.k-i-search').hide();
            listFilter.append('<a href="javascript:;" class="newItem">+ Add</a>');
        }
        // check the number of items in the list
        if (listScroller.find('ul > li').length > 0) {
            listFilter.find('.k-i-search').show();
            listFilter.find('.newItem').remove();
       }
    }, 500); // 500 ms delay before running code
}); 

有几个原因可以解释为什么你想要实现的目标没有发生。一切都与您在keyup函数中选择项目的方式有关。我会尽力解释原因：

1. 您正在选择带有k-list-scroller的所有元素...其中有3个。所以这个表达式的结果

   $('.k-list-scroller ul > li').length === 0

在给定的上下文中将始终为假

2. 这里也发生了同样的情况...

   $('.k-list-filter .k-i-search').hide();

当您尝试隐藏放大镜图标时

3. 最后但并非最不重要的一点是，当满足上述条件时，您需要延迟内部代码块的执行，因为 kendo/telerik 会操作下拉项并使它们可见，换句话说，一旦您隐藏搜索图标 telerik 就会立即显示它。

这是一个工作代码片段...

$(document).ready(function() {
  // set up the delay function
  var delay = (function(){
    var timer = 0;
    return function(callback, ms) {
      clearTimeout (timer);
      timer = setTimeout(callback, ms);
    };
  })();
  $(".selectBox").kendoDropDownList({
    filter: "contains"
  });
  // set up the event handler
  $(".k-list-filter input").keyup(function () {
  
   var self = this;
    // wait for Kendo to catch up
    delay(function () {
      // check the number of items in the list and make sure we don't already have an add link
      
      var itemsFound = $(self).parents('.k-list-container').find(".k-list-scroller ul > li").length;
      
      if (itemsFound === 0 && !($(".newItem").length)) {
      console.log("Adding new");
      setTimeout(function(){
        $(self).parents('.k-list-container').find('.k-list-filter .k-i-search').hide();
        $(self).parents('.k-list-container').find('.k-list-filter').append('<a href="javascript:;" class="newItem">+ Add</a>');
        }, 50);
      }
      // check the number of items in the list
      if ($('.k-list-scroller ul > li').length > 0) {
        $('.k-list-filter .k-i-search').show();
        $('.k-list-filter .newItem').remove();
      }
    }, 500); // 500 ms delay before running code
  });    
});

body{font-family:Verdana;font-size:12px;margin:50px 10px;}
.k-header{border:1px solid #ccc;background:#fff;}
.newItem{position:absolute;top:8px;right:10px;}

<link rel="stylesheet" type="text/css" href="//kendo.cdn.telerik.com/2016.1.112/styles/kendo.material.min.css"/>
<link rel="stylesheet" type="text/css" href="//kendo.cdn.telerik.com/2016.1.112/styles/kendo.common-material.min.css"/>
<link rel="stylesheet" type="text/css" href="//kendo.cdn.telerik.com/2016.1.112/styles/kendo.material.min.css"/>
<link rel="stylesheet" type="text/css" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css"/>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<script type="text/javascript" src="//kendo.cdn.telerik.com/2016.1.112/js/kendo.all.min.js"></script>
<script type="text/javascript" src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<div class="row">
  <div class="col-xs-4">
    <div class="field">
      <select class="selectBox">
        <option>-- Select 1 --</option>
        <option>Lorem</option>
        <option>Ipsum</option>
        <option>Dolar</option>
      </select>
    </div>
  </div>
  <div class="col-xs-4">
    <div class="field">
      <select class="selectBox">
        <option>-- Select 2 --</option>
        <option>Lorem</option>
        <option>Ipsum</option>
        <option>Dolar</option>
        <option>Sit amet lieu</option>
      </select>
    </div>
  </div>
  <div class="col-xs-4">
    <div class="field">
      <select class="selectBox">
        <option>-- Select 3 --</option>
        <option>Lorem</option>
        <option>Ipsum</option>
        <option>Dolar</option>
      </select>
    </div>
  </div>
</div>