Javascript 如何获取jquery select下拉列表的多个值？

我的多选下拉列表如下

<div class="col-sm-3 text-left form-group form-group000 form-horizontal" >
                          <span class="btn-block dropdown-checkbox-example dropdown-checkbox dropdown btn-gray">  </span>
                      </div>

Jquery代码如下：

 <script src="js/bootstrap-dropdown-checkbox.js"></script>

功能列表（需要，选中）{
var结果=[]；
对于（变量i=0；i

我的问题是我想在数据库中添加选定的值。那么如何在请求中获得下拉选择的值呢

function list(want, checked) {
    var result = [];
    for (var i = 0; i < size; i++) {
      result.push({
        id: i,
        label: 'Item #' + i,
        isChecked: checked === undefined ? !!(Math.round(Math.random() * 1)) : checked
      });
    }
    return result;

  }

  var widget, alt;

  var tab = [
    { id: "1", label: "Buy.", isChecked: false },
    { id: "2", label: "Sale", isChecked: false },
    { id: "3", label: "Rent", isChecked: false }
  ];

  $('.dropdown-checkbox-example').dropdownCheckbox({
    data: tab,
    autosearch: true,
    title: "My Dropdown Checkbox",
    hideHeader: false,
    showNbSelected: true,
    templateButton: '<a class="dropdown-checkbox-toggle btn-block btn btn-default pad-space4" style=" text-decoration:none;" data-toggle="dropdown" href="#"><span style="color:#000">I want to</span> <span class="dropdown-checkbox-nbselected"></span><b class="caret"></b>'
  });