The following two examples are very simple examples for AJAX in asp.net. The functions of the two examples are the same.
ref: "how to use CallbackEventHandler, the example", http://ramones.blogsome.com/2007/06/08/how-to-use-callbackeventhandler-the-example/
Use only single file.
<%@Page Language="VB" %>
<%@Implements Interface="System.Web.UI.ICallbackEventHandler" %>
<script runat="server">
Dim result as string= string.Empty
' Define method that processes the callbacks on server.
'receive the argument transfered from client-side
Public Sub RaiseCallbackEvent(ByVal eventArgument As String) Implements System.Web.UI.ICallbackEventHandler.RaiseCallbackEvent
result = eventArgument & " and more"
End Sub
' Define method that returns callback result.
' return the result to the client-side function which is specified in the GetCallbackEventReference
Public Function GetCallbackResult() As String Implements System.Web.UI.ICallbackEventHandler.GetCallbackResult
return result
End Function
</script>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
<script language="javascript" type="text/javascript">
// the <% %> code will becomes a js function when the page is displayed at the browser.
function jscall(arg,context)
{
<%= Page.ClientScript.GetCallbackEventReference(me, "arg", "receiveFunction", "context")%>;
}
// result from the server-side is passed to the "result" argument
function receiveFunction(result,context)
{
form1.test.value=result ;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<input name="test" value='I love kerry more' size="100"/>
<input type="button" value="call" onclick="jscall(form1.test.value,'none')" />
</form>
</body>
</html>
Use Code behide.
file: test_vb1.aspx
<%@Page Language="VB" CodeFile="test_vb1.aspx.vb" Inherits="test_vb1" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Untitled Page</title>
<script language="javascript" type="text/javascript">
// the <% %> code will becomes a js function when the page is displayed at the browser.
function jscall(arg,context)
{
<%= Page.ClientScript.GetCallbackEventReference(me, "arg", "receiveFunction", "context")%>;
}
// result from the server-side is passed to the "result" argument
function receiveFunction(result,context)
{
form1.test.value=result ;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<input name="test" value='I love kerry more' size="100"/>
<input type="button" value="call" onclick="jscall(form1.test.value,'none')" />
</form>
</body>
</html>
file: test_vb1.aspx.vb
Partial Class test_vb1
Inherits System.Web.UI.Page
Implements System.Web.UI.ICallbackEventHandler
Dim result As String = String.Empty
' Define method that processes the callbacks on server.
'receive the argument transfered from client-side
Public Sub RaiseCallbackEvent(ByVal eventArgument As String) Implements System.Web.UI.ICallbackEventHandler.RaiseCallbackEvent
result = eventArgument & " and more"
End Sub
' Define method that returns callback result.
' return the result to the client-side function which is specified in the GetCallbackEventReference
Public Function GetCallbackResult() As String Implements System.Web.UI.ICallbackEventHandler.GetCallbackResult
Return result
End Function
End Class