onchange event for html.dropdownlist

If you don't want jquery then you can do it with javascript :-

@Html.DropDownList("Sortby", new SelectListItem[] {      new SelectListItem() { Text = "Newest to Oldest", Value = "0" },      new SelectListItem() { Text = "Oldest to Newest", Value = "1" }},     new { @onchange="callChangefunc(this.value)" });<script>    function callChangefunc(val){        window.location.href = "/Controller/ActionMethod?value=" + val;    }</script>

You can do this

@Html.DropDownList("Sortby", new SelectListItem[] { new SelectListItem()   {        Text = "Newest to Oldest", Value = "0" }, new SelectListItem() { Text = "Oldest to Newest", Value = "1" } , new       {           onchange = @"form.submit();"       }})

You can try this if you are passing a value to the action method.

@Html.DropDownList("Sortby", new SelectListItem[] { new SelectListItem() { Text = "Newest to Oldest", Value = "0" }, new SelectListItem() { Text = "Oldest to Newest", Value = "1" }},new { onchange = "document.location.href = '/ControllerName/ActionName?id=' + this.options[this.selectedIndex].value;" })

Remove the query string in case of no parameter passing.