ASP.NET client side coding has two aspects:
- 1-Client
side scripts : It runs on the browser and
in turn speeds up the execution of page. For example, client side data
validation which can catch invalid data and warn the user accordingly
without making a round trip to the server.
- 2-Client
side source code : ASP.NET pages generate this.
For example, the HTML source code of an ASP.NET page contains a number of
hidden fields and automatically injected blocks of JavaScript code, which
keeps information like view state or does other jobs to make the page
work.
I.
Client
Side Scripts
All ASP.NET server controls allow calling client side code written
using JavaScript or VBScript. Some ASP.NET server controls use client side
scripting to provide response to the users without posting back to the server.
For example, the validation controls.
Apart from these scripts, the Button control has a property
OnClientClick, which allows executing client-side script, when the button is
clicked.
The traditional and server HTML controls have the following events
that can execute a script when they are raised:
Event
|
Description
|
onblur
|
When the control loses focus
|
onfocus
|
When the control receives focus
|
onclick
|
When the control is clicked
|
onchange
|
When the value of the control changes
|
onkeydown
|
When the user presses a key
|
onkeypress
|
When the user presses an alphanumeric key
|
onkeyup
|
When the user releases a key
|
onmouseover
|
When the user moves the mouse pointer over
the control
|
onserverclick
|
It raises the ServerClick event of the
control, when the control is clicked
|
II.
Client
Side Source Code
We have already discussed that, ASP.NET pages are generally
written in two files:
- The
content file or the markup file ( .aspx)
- The
code-behind file
The content file contains the HTML or ASP.NET control tags and
literals to form the structure of the page. The code behind file contains the
class definition. At run-time, the content file is parsed and transformed into
a page class.
This class, along with the class definition in the code file, and
system generated code, together make the executable code (assembly) that
processes all posted data, generates response, and sends it back to the client.
Consider the simple page:
<%@ Page
Language="C#" AutoEventWireup="true"
CodeBehind="Default.aspx.cs"
Inherits="clientside._Default"
%>
<!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>
</head>
<body>
<form id="form1"
runat="server">
<div>
<asp:TextBox
ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button
ID="Button1" runat="server"
OnClick="Button1_Click" Text="Click" />
</div>
<hr />
<h3> <asp:Label
ID="Msg" runat="server" Text="">
</asp:Label> </h3>
</form>
</body>
</html>
|
When this page is run on the browser, the View Source option shows
the HTML page sent to the browser by the ASP.Net runtime:
<!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>
<title>
Untitled Page
</title>
</head>
<body>
<form name="form1"
method="post" action="Default.aspx"
id="form1">
<div>
<input type="hidden"
name="__VIEWSTATE" id="__VIEWSTATE"
value="/wEPDwUKMTU5MTA2ODYwOWRk31NudGDgvhhA7joJum9Qn5RxU2M="/>
</div>
<div>
<input type="hidden"
name="__EVENTVALIDATION" id="__EVENTVALIDATION"
value="/wEWAwKpjZj0DALs0bLrBgKM54rGBhHsyM61rraxE+KnBTCS8cd1QDJ/"/>
</div>
<div>
<input
name="TextBox1" type="text" id="TextBox1"
/>
<input type="submit"
name="Button1" value="Click" id="Button1" />
</div>
<hr />
<h3><span
id="Msg"></span></h3>
</form>
</body>
</html>
|
