26. WEB METHOD(.ASMX)
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding
(ConformsTo = WsiProfiles.BasicProfile)]
[ScriptService]
public class Service : System.Web.Services.WebService
{
public Service () {}
[WebMethod]
public int GetMessage()
{
return string.Empty;
}
}
2017/5/16 26
var xmlHttp;
function UpdateCountries()
{
//Let us create the XML http object
xmlHttp = null;
if(window.XMLHttpRequest)
{
//for new browsers
xmlHttp = new XMLHttpRequest();
}
else if(window.ActiveXObject)
{
//for old ones
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
if(xmlHttp != null)
{
//eveyhthing so far is just fine, lets proceed
//Retreive the value of the first drop down list
var contName = document.getElementById('<%=drpContinent.ClientID %>').value;
//Handle the response of this async request we just made(subscribe to callback)
xmlHttp.onreadystatechange=state_Change;
//Pass the value to a web page on server as query string using XMLHttpObject.
xmlHttp.open("GET", "frmForAjaxCalls.aspx?cont=" + contName, true);
xmlHttp.send(null);
}
}
//Handle the response of this async request
function state_Change()
{
if (xmlHttp.readyState==4)
{
// 4 = “loaded”
if (xmlHttp.status==200)
{
//request was successful. so Retrieve the values in the response.
var countries = xmlHttp.responseText.split(';');
var length = countries.length;
//Change the second dropdownlists items as per the new values foudn in response.
//let us remove existing items
document.getElementById('<%=drpCountry.ClientID %>').options.length = 0;
//Now add the new items to the dropdown.
var dropDown = document.getElementById('<%=drpCountry.ClientID %>');
for (var i = 0; i < length - 1; ++i)
{
var option = document.createElement("option");
option.text = countries[i];
option.value = countries[i];
dropDown.options.add(option);
}
}
}
}
