Using JavaScript Effectively in ASP.NET 2.0 - Part 1
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by Satheesh Babu
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RegisterClientScriptBlock() Methods

Page.RegisterStartUpScript() and the Page.RegisterClientScriptBlock() methods in .NET Framework 1.x are now considered obsolete. These two methods are now packed with ClientScriptManaget class. The RegisterClientScriptBlock() method allows you to place a JavaScript function at the top of the page and it gets executed on startup of the page (when loading the page in the browser). There is an additional method called IsClientScriptBlockRegistered() in ClientScriptManager which will return true if a script block is already registered with the same key, hence, we can prevent the duplicate script registration.

There are 2 overloads for this method.

Listing 1 - RegisterClientScriptBlock Overloads

ClientScriptManager.RegisterClientScriptBlock (Type typeofscript, String key, 
String script) 
ClientScriptManager.RegisterClientScriptBlock (Type typeofscript, String key, 
String script, Boolean addScriptTags)

Usage

Placing this code on page load or a button click makes the script to fire on the start up of subsequent postback.

Listing 2 - 1st overload

ClientScriptManager script = Page.ClientScript;
if (!script.IsClientScriptBlockRegistered(this.GetType(), "Alert"))
{
script.RegisterClientScriptBlock(this.GetType(), "Alert""<script type=text/javascript>alert('hi')</script>");
}

Listing 3 - 2nd overload

ClientScriptManager script = Page.ClientScript;
if (!script.IsClientScriptBlockRegistered(this.GetType(), "Alert"))
{
script.RegisterClientScriptBlock(this.GetType(), "Alert""alert('hi')",true);
}

Figure 1 - RegisterClientScriptBlock Output

As I said earlier, these methods will make the script block to execute on the startup, thus we can see the alert box before the controls are actually rendered.


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User Comments

Title: Easy to udersatnd   
Name: Raj kumar
Date: 2011-01-18 5:58:27 AM
Comment:
This the example that how we can add additionl attribute on any asp:.. control .
First we register ClientSide Script at the time of page_load then it works.
code is all-ready given there.
ok by
Title: Javascript   
Name: mohamed
Date: 2010-11-24 8:11:08 AM
Comment:
There is a problem in the stress at which any request for the page, there will be an invitation to the confirmation message that you need to be placed in the confirmation message within the event of a button, instead of the event page, although the occurrence of this call is also a confirmation message. What is the solution
Title: Javascript   
Name: mohamed
Date: 2010-11-24 7:58:03 AM
Comment:
There is a problem in the stress at which any request for the page will be a caller confirmation message
Title: Javascript   
Name: Praveen
Date: 2010-03-10 1:59:54 AM
Comment:
Simple examples to understand the concepts.Excellent
Title: JavaScript on form load   
Name: yc
Date: 2009-05-11 4:54:00 AM
Comment:
Thanks sir,
JavaScript on form load.
That's what I was googling for 2 days.
Regards
Title: Listing6 problem   
Name: O M
Date: 2009-04-23 6:02:23 PM
Comment:
Looks like Listing6 should be for "RegisterStartupScript Output" instead it is same as Listing1.
Title: Web Developer   
Name: Dhananjay
Date: 2009-04-13 7:56:31 AM
Comment:
This is very good article.
but I have question regarding - RegisterOnSubmitStatement.
On my page there are two buttons first one is Show - to display data and another is Delete - to delete data.

In this condition using your code How can I show confirm box on only on delete button.
Title: Web Developer   
Name: Shilpa
Date: 2009-04-07 6:09:04 AM
Comment:
Javascript functionality explained in such a simple technical terms. Its wonderful.
Satish Babu, keep it up.
Title: web developer   
Name: xiaohong
Date: 2009-04-06 2:56:36 PM
Comment:
nice organized article, thanks!
Title: Dan   
Name: Dan
Date: 2009-04-01 10:00:10 AM
Comment:
I didn't know about the onsubmitscript. Thanks's
Title: Nice article   
Name: Anas
Date: 2009-04-01 3:42:09 AM
Comment:
Nice article thanks
i like it
Title: Part 2   
Name: Joe
Date: 2009-03-25 12:20:57 PM
Comment:
You can read the 2nd part here,
http://www.codedigest.com/Articles/ASPNET/221_Using_JavaScript_Effectively_in_ASPNet_20_%e2%80%93_PART_2.aspx
Title: Can you provide Part 2 Article for the same   
Name: Sree
Date: 2009-01-08 7:14:12 AM
Comment:
Hi,
Nice article ragarding clientscriptmanager class.
It would be great if you provide Part 2 continuation link for the same.
Title: Good Article   
Name: greeny
Date: 2008-12-20 2:52:31 AM
Comment:
Hi,

good to see easily understandable article.
Title: Great Article   
Name: J
Date: 2008-12-09 5:46:12 AM
Comment:
This was the first article I read on RegisterStartupScript.
Very easy to understand article with nice examples.
Thanks a lot for shairing this
Title: Programmer   
Name: Tonci Korsano
Date: 2008-09-30 2:38:46 PM
Comment:
Hi,

I think this is a good article. RegisterOnSubmitStatement() Method was explained in a simple way. I might have to use this method. However, I have read that in these methods it is more efficient to use typeOf(this) or typeOf(Page) instead of this.getType() or Page.getType()

Tonci.
Title: RE: how to execute onsumit in between the server code   
Name: Mikalai
Date: 2008-09-26 10:51:03 AM
Comment:
To Nonu:
do not be confused with server and client side code. alert could be only displayed when server side code is finished and result html is sent to the client.
Title: how to execute onsumit in between the server code   
Name: Nonu
Date: 2008-09-25 11:06:28 AM
Comment:
Hi
Your article is helped me a lot to understand clientscript class.
but i want to execute a alert in between the server side code.
Title: Good Article   
Name: Joe
Date: 2008-09-17 11:47:12 PM
Comment:
Satheesh,
Your article is really good! It is really useful to people like me!
Thanks again!
Title: Mr.   
Name: kmanral
Date: 2008-09-17 2:52:58 PM
Comment:
only useful part of article is the link to MSDN. oops...

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