June 2002
Intermediate to advanced
816 pages
28h 12m
English
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Name
IsPostBack
Synopsis
Boolean = Page.IsPostBack
Returns
a Boolean
value that indicates if the page is loaded for the first time
(False) or is loaded as a result of the client
postback (True). This property comes handy for the
logic that needs to be executed the first time the page is executed
or every time the page is posted back to itself, depending on how you
structure your If statement.
Parameters
-
Boolean A Boolean value that indicates if the page is loaded for the first time or is loaded as a result of the client postback.
Example
The code example below uses the IsPostBack property to display
different messages in the Label control, depending on whether the
page is loaded for the first time or is loaded as a result of the
client postback. The first time the page is loaded, the IsPostBack
property returns False, causing the string
“Non-PostBack” to be displayed.
Clicking the button posts the page back to itself, causing IsPostBack
to return True and the string
“PostBack” to be displayed.
<%@ Page Language="vb" %>
<html>
<head>
<title></title>
<script runat="server">
Sub Page_Load( )
If Page.IsPostBack Then
Message.Text = "PostBack"
Else
Message.Text = "Non-PostBack"
End If
End Sub
</script>
</head>
<body>
<form runat="server">
<asp:button id="post" Text="Post page" runat="server"/>
<asp:label id="Message" runat="server"/>
</form>
</body>
</html>Notes
The IsPostBack property will return True only for
pages that contain a <form> element with the
runat="server" attribute and at least ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.