Dynamically add content to one Dropdownlist on the basis of selection of other Dropdownlist

<script runat="server" >
public void Page_Load ( object sender, EventArgs e)
{
MyDropDownList.Attributes.Add("OnChange", "FillCity()") ;
MyDropDownList.Items.Add(new ListItem("Selecy Country", ""));
MyDropDownList.Items.Add(new ListItem("India", "IND"));
MyDropDownList.Items.Add(new ListItem("United Kingdom", "UK"));
MyDropDownList.Items.Add(new ListItem("United States", "US"));
MyDropDownList.Items.Add(new ListItem("France", "FR"));
MyDropDownList.Items.Add(new ListItem("Srilanka", "SR"));
DropDownList.Items.Add(new ListItem("Selecy City", ""));
String strString;
strString = "<script language='JavaScript' >"; 
strString += "JCountry = new Array(15);";
strString += "JCountry[1] = 'IND';";
strString += "JCountry[2] = 'IND';";
strString += "JCountry[3] = 'US';";
strString += "JCountry[4] = 'US';";
strString += "JCountry[5] = 'US';";
strString += "JCountry[6] = 'UK';";
strString += "JCountry[7] = 'UK';";
strString += "JCity = new Array(20);";
strString += "JCity[1] = 'Mumbai';";
strString += "JCity[2] = 'Pune';";
strString += "JCity[3] = 'New York';";
strString += "JCity[4] = 'Chicago';";
strString += "JCity[5] = 'Washignton';";
strString += "JCity[6] = 'London';";
strString += "JCity[7] = 'Leeds';";
strString += "<" + "/" + "script>";
Response.Write(strString);
}
public void alphaSubmit(object sender , EventArgs e)
{

}
</script>

<script language="JavaScript" >
function FillCity()
{
str = document.all["MyDropDownList"].value ;
document.all["DropDownList"].length=0;
soption = "Select City"
st = new Option(soption,"");
document.all["DropDownList"].add(st)
for (i=1;i<8;i++){
if (JCountry[i] == str){
soption = JCity[i];
st = new Option(soption,soption);
document.all["DropDownList"].add(st)
}

}

}
</script>

<H1>Combination OF C# and JavaScript </H1><br>
By Laxmikant Shrotri
<Form name="MyForm" runat="server">
<asp:Dropdownlist id="MyDropDownList" DataValueField = "CountryCode" DataTextField = "Country" runat="server" />
<asp:Dropdownlist id="DropDownList" DataValueField = "CountryCode" DataTextField = "Country" runat="server" />