jquery – JavaScript运行时错误：无法获取未定义或空引用的属性’forEach’

我有一个aspx母版页应用程序,我在子aspx页面的asp：content部分有两个下拉列表控件.其中一个控件是从sql数据库填充的.另一个是根据从第一个下拉列表中选择的项目填充的.我试图在我的代码中使用 this solution,但是我收到一个错误：

如何根据所选的州显示城市名称？
我的代码块是：

<link rel="stylesheet" href="//code.jquery.com/ui/1.11.1/themes/smoothness/jquery-ui.css">
  <script src="//code.jquery.com/jquery-1.10.2.js"></script>
  <script src="//code.jquery.com/ui/1.11.1/jquery-ui.js"></script>

    <script type="text/javascript">
        AL = new Array('Birmingham','Montgomery','Tuscaloosa');
        FL = new Array('Miami','FtLauderDale','Jacksonville');
        GA = new Array('Atlanta','Macon','Athens');

        populateSelect();

        $(function () {

            $('#ddlState').change(function () {
                populateSelect();
            });

        });

        function populateSelect() {
            category = $('#ddlState').val();
            $('#ddlCity').html('');

            eval(category).forEach(function (t) {
                $('#ddlCity').append('<option>' + t + '</option>');
            });
        }
    </script>  

<asp:DropDownList ID="ddlCity" runat="server" CssClass="stdFldWidth" onchange="setFDFlag()">
</asp:DropDownList>    

<asp:DropDownList ID="ddlState" runat="server" CssClass="stdFldWidth" DataSourceID="dsUSState"
    DataTextField="US_State" DataValueField="State_ID" AutoPostBack="true" > 
</asp:DropDownList>

更新：

Protected Sub ddlState_SelectedIndexChanged(sender As Object,e As System.EventArgs) Handles ddlType.SelectedIndexChanged
If ddlState.SelectedValue = "FL" Then
    DisplayRegulation(FL)
End If

<asp:DropDownList ID="ddlCity" runat="server" CssClass="stdFldWidth ddlCity" onchange="setFDFlag()">
</asp:DropDownList>    

<asp:DropDownList ID="ddlState" runat="server" CssClass="stdFldWidth ddlState" DataSourceID="dsUSState"
    DataTextField="US_State" DataValueField="State_ID" AutoPostBack="true" > 
</asp:DropDownList>

$(function () {
    var states = {
        AL: ['Birmingham','Tuscaloosa'],FL: ['Miami','Jacksonville'],GA: ['Atlanta','Athens']
    };

    function populateSelect() {
        $('.ddlCity').empty();

        var stateSelected = $('.ddlState').val();

        if (stateSelected) {
            states[stateSelected].forEach(function (sel) {
                $('<option>').val(sel).text(sel).appendTo($('.ddlCity'));
            });
        }
    }

    populateSelect();

    $('.ddlState').on('change',function() { 
        populateSelect();

        return true;
    });
});