如何附加到select2中现有的下拉选项之一？

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

$('#mySelect').select2();

$('#mySelect').append('<option value="option4">Option 4</option>');

$('<option value="option5">Option 5</option>').insertAfter('#mySelect option[value="option2"]');

$('#mySelect option[value="option3"]').replaceWith('<option value="option6">Option 6</option>');

$('#mySelect option[value="option1"]').remove();