How to swap 2 @Html.DropDownListFor with Jquery/JS

Question

I found some examples in SO. But none of them worked for me. I want to swap values of 2 @Html.DropDownListFor each other. Both DropDownList contains the same set of values except the default value to show. Below is my code.

<div class="currency_swap">
<p>
    <label>From</label>
    <div class="swap_dropdown">
        @Html.DropDownListFor(m => m.SourceCurrencyname, new SelectList(ViewBag.CurrencyNames, "Currency_Code", "Currency_Code"), "---- All ----")
    </div>
</p>
<div><input type="button" id="swap_up" value="&#x25B2" class="swap" /></div>
<p>
    <label>To</label>
    <div class="swap_dropdown">@Html.DropDownListFor(m => m.TargetCurrencyname, new SelectList(ViewBag.CurrencyNames, "Currency_Code", "Currency_Code"), "Agency Currency")</div>
</p>
</div>

<script type="text/javascript">
$(".swap").click(function () {
    var row = $(this).closest(".currency_swap");
    var start = row.find("swap_dropdown:first select");
    var end = row.find("swap_dropdown:last select");
    var temp = start.val();
    start.val(end.val());
    end.val(temp);
});
</script>

Answer 1

The start and end variables are not correctly set. The selectors could be something like the following.

var start = row.find(".swap_dropdown select:first");
var end = row.find(".swap_dropdown select:last");

The rest of the code worked, see js-fiddle here.