Sorting values asc and desc on multiple dropdowns

index.html

<select class="ddlList">
    <option value="3">Three</option>
    <option value="1">One</option>
    <option value="1">one</option>
    <option value="1">a</option>
    <option value="1">b</option>
    <option value="1">A</option>
    <option value="1">B</option>
    <option value="0">Zero</option>
    <option value="2">Two</option>
    <option value="8">Eight</option>
</select>

<select class="ddlList">
    <option value="3">Three</option>
    <option value="1">One</option>
    <option value="1">one</option>
    <option value="1">a</option>
    <option value="1">b</option>
    <option value="1">A</option>
    <option value="1">B</option>
    <option value="0">Zero</option>
    <option value="2">Two</option>
    <option value="8">Eight</option>
</select>
<input type="button" id="btnSort" Value=" Sort Dropdown By Text " />

script.js

//, attr, order

var sortSelect = function (select, attr, order) {
    if(attr === 'text'){
        if(order === 'asc'){
            $(select).html($(select).children('option').sort(function (x, y) {
                return $(x).text().toUpperCase() < $(y).text().toUpperCase() ? -1 : 1;
            }));
            $(select).get(0).selectedIndex = 0;
            e.preventDefault();
        }// end asc
        if(order === 'desc'){
            $(select).html($(select).children('option').sort(function (y, x) {
                return $(x).text().toUpperCase() < $(y).text().toUpperCase() ? -1 : 1;
            }));
            $(select).get(0).selectedIndex = 0;
            e.preventDefault();
        }// end desc
    }

};

//, attr, order
$(document).ready(function () {

    $('#btnSort').click(function (e) {
       $(".ddlList").each(function(){
        sortSelect($(this), 'text', 'asc'); 
       })
    }); // event listener click

});