在使用tablesorter.filterformatter小部件时，如何以编程方式从select2下拉列表中进行选择？

<select id="mySelect">
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

$(document).ready(function() {
  $('#mySelect').select2();
});

$(document).ready(function() {
  $('table').tablesorter({
    theme: 'blue',
    widgets: ['filter'],
    widgetOptions: {
      filter_formatter: {
        // 自定义过滤器函数
        '.select-filter': function($cell, indx, column, txt, search) {
          // 获取select2选择的值
          var selectedValue = $('#mySelect').val();
          // 判断当前单元格的值是否等于选择的值
          return selectedValue === txt;
        }
      }
    }
  });
});

<table>
  <thead>
    <tr>
      <th>Name</th>
      <th>Age</th>
      <th class="select-filter">Country</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>John</td>
      <td>25</td>
      <td>USA</td>
    </tr>
    <tr>
      <td>Jane</td>
      <td>30</td>
      <td>Canada</td>
    </tr>
    <tr>
      <td>Mike</td>
      <td>35</td>
      <td>USA</td>
    </tr>
  </tbody>
</table>