Develop Reference

Javascript timer

I have a set of objects and each those object keep track of some strings.
Those objects are created at page load and stored in an object array.
I have four user controls in ascx file that displays those strings of a particular object at a time.
And also I have a play button in the same ascx file which is default set to play.
When I load the ascx it displays the first set of strings in a particular object.
And after 5 second time interval iy should display the second set of strings in the next object. When the play button pushed, it should move into pause state also.
Can anybody give me a start to achieve this requirement. my code behind file is C#

Fundamentally, you want a 'Slideshow' of your ASCX controls. A common way to do this is by having all your ASCX's visible and then use Javascript and CSS to make one visible at a time.
Google for 'html css javascript slideshow'.
http://www.catswhocode.com/blog/top-10-javascript-slideshows-carousels-and-sliders

Just realised you might want to achieve this via front-end JavaScript as per your question title? In which case, you will need the setInterval function, and your array of data available in the DOM.
Suppose your button is
<asp:ImageButton src="source.jpg" class="btnPlay" alt="Play" />
Your JavaScript (using jQuery) could be along the lines of:
$(function() {
$('.btnPlay').click(function() {
$(this).toggleClass('btnPause');
if($(this).hasClass('btnPause') {
yourHandlerID = setInterval ("yourHandler()", 5000 );
} else {
clearInterval (yourHandlerID);
}
});
});
You can also do this via C# code behind using the timer class, example like:
http://www.csharphelp.com/2006/02/c-timer-demo/
And everytime the timer triggers the event handler you define, you can reiterate through your array, display what you want.
The toggle pause button would be just stopping the timer.
Microsoft reference:
http://msdn.microsoft.com/en-us/library/system.timers.timer(VS.71).aspx

stop setting onclick event for asp:LinkButton if no OnClick event was explicitly defined

How do I setup a default setting so that if I do not set an OnClick (i.e the asp.net OnClick attribute) explicitly for an asp:LinkButton tag, it will not render an onclick(html attribute for javascript) attribute client side? By default, asp.net adds an onclick='doPostBack....' for the LinkButton.
Case for use:
There is a LinkButton tag on the page. For this page, if the user has one friend, I only want to run client side code if the button is clicked and would not for any reason want to make a post back. If the user has more than one friend I would want a click to trigger a postback.
Solutions that include the following are not helpful:
Using any asp.net Ajaxtoolkit
Dynamically switching the control type (i.e. if friends == 1 use a asp:Hyperlink)
-I want to avoid this because it is not scalable. There might be many cases where I want an asp:Link tag to do a postback or to not do a postback depending on the user context or user attributes
Using OnClientClick (I am using jQuery would like to avoid this)
Solution that would be helpful if possible:
If I could see server side at runtime whether an OnClick event was explicitly set on an asp:LinkButton tag, this would solve my problem, too. any ideas?

How about rather than dynamically switching the controls (as you mentioned is a solution you don't want), you could always use an asp:HyperLink and set the NavigateUrl property to redirect your page back to itself with a query string of some sort indicating what was clicked.
If you don't want the post to happen at all, simply leave the NavigateUrl property blank.
Of course, this will be pretty worthless if the rest of the page is dependent on ViewState and such.

http://forums.asp.net/t/1129106.aspx
This link explains how to see server side at runtime whether an OnClick event was explicitly set using reflection

confirm message box

I have a save button which when clicked should make some changes in the database.
if (bFound== false)
{
// Giving the warning message
// If user presses cancel then abort
// Prepare the list of dbId needs to be deleted
deletedBSIds.Add(dbId);
}
Here if the bFound field is true it should not execute the above statement, but if it is false it should go in the condition and then ask if the user want to save changes "yes" or "no".
If the user says yes it should go to the command "deletedBSIds.Add(dbId);" and keep executing further but if the user presses No it should basically abort and do nothing at all.
Is there a way to do this?
Any help would be appreciated.
This is a server side event. so i think cannot add a click event in my button/..
Here the message box only pops up if the bFoung field is false. or else it will not pop up at all.
Please correct me if u feel i am wrong..
thanks

You'll want to add the following to the button:
button.OnClientClick = "return ConfirmThis();";
You'll then need to add the ConfirmThis function to the Page:
Page.ClientScript.RegisterScriptBlock(GetType(), "ConfirmThis",
#"function ConfirmThis() {
if(condition) { //where condition checks the bfound element.
return confirm(""Are you sure you want to delete this?"");
}
return true;
}");
Doing this approach you're going to want to try and be able to test the bfound condition on the client side in the javascript. If the bfound value is stored in a textbox or HiddenField you should use the document.getElementById function. If the bfound value is known when you are creating the page, you can inject it into the ConfirmThis function directly, of pass it into the ConfirmThis function as a parameter.
Edit in response to your edit:
You have two options when trying to elicit a confirm from the user:
Using client side logic that is already sent to the browser to perform the confirm. This is the example that I have given above.
The "Other" option is to send the page back with a modal dialog, or using the confirm box. You will then get the user's confirmation back in a completely new postback to the server. So you'll need to rethink your logic to be able to temporarily store the information from the first post back and wait for the second post back to finalize the desired action.
Of the two examples, the first option is cleaner and requires no temporary memory and saves the user an additional postback.
Because both options are going to require you to rework the logic asking for the confirm, if at all possible I would try to convert the logic required for the condition to show the confirm dialog to be able to be performed on the client's computer with javascript.
Is there any way you can precalculate the bfound variable, or at the least, send enough information for it to be calculated on the client?
If you still feel like using option 2 after all of my pleading:
use the following code (based on http://www.dotnetspider.com/resources/1521-How-call-Postback-from-Javascript.aspx:
if(bfound)
{
//save all the information you need in temporary information
ViewState["InformationINeedToFinishAfterPostback"] = ImportantInformation;
Page.ClientScript.RegisterScriptBlock(GetType(), "postbackmethod", Page.ClientScript.GetPostBackEventReference(this, "MyCustomArgument"));
Page.ClientScript.RegisterStartupScript(GetType(), "startupconfirm",
#"if(confirm(""are you sure?"") {
__doPostBack('__Page', 'MyCustomArgument');
}");
}
Now to handle the postback add the following code to your page_load:
if(Request("__EVENTARGUMENT") == "MyCustomArgument")
{
ImportantInformation = (CastToAppropriateType)ViewState["InformationINeedToFinishAfterPostback"];
//finalize the desired action here.
}
But... I would still recommend the first option. But now you have the code you will need for both options. Also, I didn't test this code, so you're bound to encounter syntactic problems, but it gets you on the right track.

I'm not all that sure what bfound is supposed to represent, but you can't execute 1/2 way through some server code and then go back to the client- ASP.NET does not work that way.
Typically you will do the confirmation with some client side JavaScript. Google ASP.NET Yes/no confirm to find lots of different ways to do this...
Once you've done this you can then conditionally execute the server side code.

You could use the Javascript confirm() function to display a dialog box to the user with 'OK' and 'Cancel' prompts. You could then store the user's choice in a hidden field and trigger a postback. This article explains how to render Javascript code to the client using ASP.NET.

Since you are using ASP.NET you can add an attribute to your button:
btnDelete.Attributes.Add("onclick", "return confirm('Are you sure?');");
Where btnDelete is your Button.

Persist Textbox in cookie/session automaticly

I am attempting to persist what the users enters into a textbox without them clicking save. It would simply save what the user entered into the textbox so when they navigate away and then back to the page it will be reloaded. once they are click "done" the session will be removed.
I have been trying to do this with Jquery but I have been struggling as I am fairly new to JavaScript, can anyone point me in the right direction?

You can use the onChange event of the textbox to call your save routine everytime the user changes the text; alternatively you can run a saving function every while using the setTimeout javascript function. Like RaYell said, you can store your values inside a cookie. If you use JQuery, you can take advantage from http://plugins.jquery.com/project/Cookie which offers super simple ways to read and write cookies.

You can use a cookie to store textbox value. A nice tutorial how to use cookies is here

c# Ajax Lazy Loading

I need to populate 4 GridViews on an aspx page, but I only bind a datatable to one of them on page load. I need to pupulate the other 3 after page load.
does anyone know the best way to do this using ajax ?
Currently I'm using javascript to __doPostBack on a button that pupulates the 3 GridViews but unfortunately this forces a full page load even when using an update panel. I need the page to load, and then populate the GridViews as the datatables are returned.
any suggestions would be much apreciated.

The way you are doing it should work ok, although using jquery to populate a div via the $("#targetDiv").load("contentUrl"); function may be a cleaner way to do it. Anyway, in order to get your current implementation working, there could be a few things you want to look at:
I assume EnablePartialRendering is true on your ScriptManager (always worth checking!).
Make sure the eventTarget for the __dopostback call is set up as an async trigger for your update panels or that it is inside the UpdatePanel if you are only using one UpdatePanel. (See here for details)
Try returning false from the javascript code that executes in the onclick event handler if you have attached this to a button, to make sure the form is not being submitted normally by your browser when you click the button.

If I understand the question properly, you want the data to load after the page is in the browser. If this is the case, then you can fire an event with JavaScript when the page loads on the client.
One method I've used is to put a hidden (with CSS, not any property) button on the page and 'clicking' it with javascript. The event of the button click event will need to be wired in the page's code. Also the button would have to be in an update panel that either contains the grids you want to be bound or has the appropriate triggers to cause them to reload.
You might look at JQuery to get manage when this code gets fired. The $(document).ready(function(){ /* Your code here... */ }); method will fire after the entire DOM is available, which is faster than waiting on the entire page to load (images and so forth).