Binding Javascript to a column in WebGrid asp.net MVC

  $(document).ready(function () {

        $("#SourceTable").change(function () {
            $("#ColumnNames").empty();
            $.ajax({
                type: 'POST',
                url: '@Url.Action("GetColumn")',
                dataType: 'json',
                data: { TableName: $("#SourceTable option:selected").text() },
                success: function (str) {
                    $.each(str, function (Value, Text) {
                        //alert(Value + ' ' + Text.Value);
                        $("#ColumnNames").append('<option value ="'+Value+ '">' +
                        Text.Text + '</option>');
                    });
                },
                error: function (ex) {
                    alert('Failed to retrieve columns.' + ex);
                }
            });
            return false;
        })
    });

</script>

@wg.GetHtml(
tableStyle: "gridTable",
headerStyle: "gridHead",
rowStyle: "gridRow",
footerStyle: "gridFooter",
alternatingRowStyle: "gridAltRow",
columns: wg.Columns(
wg.Column("DestnColumn", "Destination Column"),
wg.Column("SourceTable", format: @item => Html.DropDownList("SourceTable", (IEnumerable<SelectListItem>)Model.SourceColumnModel[0].SourceTables,"Select Source")),
wg.Column("ColumnNames", format: @item => @Html.DropDownList("ColumnNames", new SelectList(string.Empty, "Value", "Text"), "Select Column", new { style = "width:200px" })),
// wg.Column(header: "SourceColumn", format: @item1 => Html.DropDownList("value1", (IEnumerable<SelectListItem>)Model.SourceColumnModel[0].SourceColumnsNames)),
wg.Column("DataSize", "Size"),
wg.Column("DataType", "Data Type"))

)
)