Submitted for your approval an UltraWebGrid with CellClickActionDefault=”RowSelect” and SelectTypeRowDefault=”Single” – an ordinary down-to-earth grid. It also posses event handler AfterSelectChangeHandler, also nothing out of the ordinary. But in a minute the aforementioned grid will exhibit properties most unusual. As the alert message ahead reads: Infragistics Bug Continue reading →
Category Archives: Javascript
ClientScript.RegisterStartupScript: script injected, but not executed
This was one weird mystery. I have used ASP.NET’s method ClientScript.RegisterStartupScript countless times to inject client-side JavaScript into page’s markup from the server-side code and it always worked perfectly. This time I created a very basic page from scratch:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>My Page</title>
<script type="text/javascript" src="script1.js" />
<script type="text/javascript" src="script2.js" />
<script type="text/javascript" src="script3.js" />
</head>
<body>
<form id="xfrmMain" runat="server">
</form>
</body>
</html>
And then injected client-side script into it:
ClientScript.RegisterStartupScript(Me.GetType, "JSCode", "ProcessData();", True)
where ProcessData() is function from one of the scripts, loaded in the HEAD tag. The script injected just fine, I got a beautiful insert at the bottom of the rendered page:
<script type="text/javascript"> //<![CDATA[ ProcessData();//]]> </script>
The problem was – it didn’d do squat – the script did not execute. Why? Continue reading →
How to load IFRAMEs in order according to priority
Let’s say you have a Web page that displays “widgets” a small islands of information. And internally those widgets are IFRAME elements, whose source is loaded dynamically from the same server at runtime in client side JavaScript. So, you have a code similar to this:
var aIframes = document.getElementsByTagName('IFRAME');
for (var I = 0; I < aIframes.length; I++) {
aIframes[I].src = aIframes[I].getAttribute('originalURL')
}
This (oversimplified) code assumes that URL for IFRAME source already stored as a custom attribute ‘originalURL’ of IFRAME element (for example placed there by server-side code), but it can equally come from other sources. This approach is usually taken so IFRAMES can initially display a static page with “Please wait. Loading…” animation meanwhile dynamically loading real data – creates a better user experience.
The code loops thru all IFRAMEs setting their SRC attribute, displaying content, so you would see something like
It’s all well and good, but there’s a small problem. SRC of IFRAMEs is assigned in order of their appearance on the page and if URLs are pointing to the same server and one of the earlier IFRAMEs takes a long time to load – it will block the rest of the IFRAMEs from loading. Continue reading →
onbeforeunload event is fired on click
onbeforeunload browser’s event fires when the window is about to navigate to another page or about to be closed. So why why would it fire when you click to call a JavaScript function that does neither of the two?
If your have your click setup similar to something like this:
<a href='javascript:doStuff()'>Click to do something</a>
or, if you’re using ASP.NET’s HyperLink control:
<asp:HyperLink ID="xhypMuLink" runat="server" NavigateURL="javascript:doStuff()"> Click to do something </asp:HyperLink>
And your “doStuff()” function doesn’t redirect or closes the window – you’d expect it just do its stuff and that’s it. But in addition to it, or rather before it onbeforeunload event fires, so if you have some code in the event handler – it will be executed, which in this case is undesirable.
Why does it happen? Continue reading →
WebDataMenu: Incorrect displaying after upgrade
This is the second post in saga titled Upgrading Infragistics Controls to a new version. Chances are that your WebDataMenu looks weird after upgrade to 2010+ version. In my case the menu had following options/features:
- It was a context popup menu, called on right mouse click
- Text of menu items was assigned dynamically at runtime in JavaScript Client code
After upgrading NetAdvantage from version 2009.2 to 2011.1 strange things started to happen. Text of the menu items was cut short, submenues appeared at wrong places it looked like something from a Dali’s painting.
Numerous experiments later I found out that the problem was with EnableScrolling property of the menu control. Setting it to False returned menu to realm of realism.
WebHierarchicalDataGrid: JavaScript errors after upgrade
Upgrading 3rd party library to a new version is bound to have problems and Infragistics is no exception. In my case I was upgrading NetAdvantage for ASP.NET from version 2009.2 to to 20011.1 and right away WebHierarchicalDataGrid started to crash client-side. If ScriptManager was in debug mode I’d get error:
Microsoft JScript runtime error: Sys.ArgumentUndefinedException: Value cannot be undefined.Parameter name: type
With ScriptManager in Release mode it’d be:
Microsoft JScript runtime error: Object expected
But always in Sys.Component.Create – it looked like grid’s client-side scripts weren’t loading at all. After A LOT of digging I found out that the culprit was grid’s server-side Bands.Clear() method. When called, it caused client-side WHDG JavaScript not to load. When that method was commented – JavaScript errors disappeared. So until Infragistics comes out with a bug fix – if you experience similar problem, try to avoid Bands.Clear() method.
Prevent Cross Site Scripting thru hidden fields
ASP.NET protects you pretty good when user tries to post a malicious content thru an entry form. With @page directive “ValidateRequest=true” (which is true by default) if anybody attempts to enter something like <script type=”text/javascript”>…nasty stuff here…</script> the page will throw HttpRequestValidationException exception: A potentially dangerous value was detected from the client…
But this does not work for some form elements, for example framework variables such as __EVENTVALIDATION or __VIEWSTATE over which user or developer do not have direct control. A maliciously crafted POST request can insert JavaScript into those elements which then can execute in user’s browser. Yes the page may crash because of invalid data, but JavaScript is still echoed to the client and gets executed. In this case ASP.NET needs a little help. Continue reading →
WebHierarchicalDatagrid: Sys.ArgumentException: Cannot deserialize on Row Expand
I have been using WebHierarchicalDataGrid with manual load on demand bands with a pretty good success until I hit this snag.
The WHDG has correctly displayed HTML fields before, but this time a column with HTML data (an HREF link to be precise) is needed as one of the grid’s DataKeyFields to provide uniqueness of the row:
Solution for UltraWebGrid missing scrollbars
I was working with classic Infragistics UltraWebGrid when noticed strange thing – even though scrollbars were enabled for the grid, the grid had fixed size and number of rows was bigger than the grid could display – no scrollbars appeared. For me it was a combination of grid being shown in a modal dialog in IE7 browser, but it could happen in other scenarios.
I also noticed when grid experienced any kind of user interaction (row added, row selected, checkbox cell checked etc.) scrollbars would magically appear. So the solution? Simulate user interaction. For example this code can be included in grid’s client-side InitializeLayout event:
function xMyGrid_InitializeLayout() {
var oGrid = igtbl_getGridById('xMyGrid')
oGrid.Rows.getRow(0).setSelected(true);
oGrid.Rows.getRow(0).setSelected(false);
}
What happens here is first row of the grid is selected and an instant later unselected. It happens so fast that there’s no visual indication. But the grid gets its “user interaction” and scrollbars appear.
Affecting page during WebDataGrid AJAX calls
When Infragistics WebDataGrid perform AJAX operations such as sorting and paging – it sends grid data directly to page’s DOM. But it also allows you to send your own custom data via server-side GridResponse object and its client-side counterpart. This feature allows you to establish effective link between server and client to perform custom operations otherwise available only during full postback or partial postback via update panel. There’re multiple cases where this can be used, let’s take a look at 3 most common:
- Updating a related control with server-side generated data
- Running a server-side generated JavaScript
- Handling server-side errors, for example Session timeout