[asp.net-mvc] Handling onchange event in HTML.DropDownList Razor MVC

I'm handling an onchange event with a selected value by simple HTML like this:

<select onchange="location = this.value;">
         <option value="/product/categoryByPage?PageSize=15" selected="selected">15</option>
         <option value="/product/categoryByPage?PageSize=30" selected="selected">30</option>
         <option value="/product/categoryByPage?PageSize=50" selected="selected">50</option>
</select>

Doing it like this:

List<SelectListItem> items = new List<SelectListItem>();
string[] itemArray = {"15","30","50"};

for (int i = 0; i < itemArray.Count(); i++)
{
    items.Add(new SelectListItem 
    { 
        Text = itemArray[i], 
        Value = "/product/categoryByPage?pageSize=" + itemArray[i]
    });
}

ViewBag.CategoryID = items;
@Html.DropDownList("CategoryID")

How can I handle onchange with @Html.DropDownList()

The way of dknaack does not work for me, I found this solution as well:

@Html.DropDownList("Chapters", ViewBag.Chapters as SelectList, 
                    "Select chapter", new { @onchange = "location = this.value;" })

where

@Html.DropDownList(controlName, ViewBag.property + cast, "Default value", @onchange event)

In the controller you can add:

DbModel db = new DbModel();    //entity model of Entity Framework

ViewBag.Chapters = new SelectList(db.T_Chapter, "Id", "Name");