Encosia - ASP.NET, AJAX, jQuery, and more

11 keystrokes that made my jQuery selector run 10x faster

ASP.NET, CSS, JavaScript, jQuery, Performance By . Updated June 30, 2010

As an ASP.NET developer working on the client-side, one problem you’ll encounter is how to reference the HTML elements that ASP.NET web controls generate. All too often, you find yourself wasting time trying to reference TextBox1, when the element is actually rendered as ctl00_panel1_wizard1_TextBox1.

Much has been written about this, including a post of my own, so I won’t go into detail about many of the workarounds. Instead, I want to take a closer look at the performance drawbacks of one popular solution: the [attribute$=value] selector.

By specifying id as the attribute in this selector, you can avoid ASP.NET’s ClientID issues completely. No matter what the framework prefixes your rendered elements with, they still “end with” the ID you specify at design time. This makes the “ends with” selector a convenient alternative to injecting a control’s ClientID property via angle-brackets.

However, are we trading performance for this convenience? If so, how much?

When Craig Shoemaker asked that question while interviewing me for an upcoming episode of Polymorphic Podcast, I realized I didn’t know the answer as clearly as I’d like. So, I decided to do a bit of benchmarking.

In this post, I’ll share the results of that benchmarking, and show you one way to significantly improve the performance of this convenient selector.

Click here to read the rest of this post »

Highslide JS .NET v4.1.4

ASP.NET, Highslide, UI By . Posted June 3, 2009

A new version of Highslide JS .NET is available today. Nothing major has changed in the .NET control, but the newer Highslide JS version includes several bug fixes, compatibility improvements, and performance benefits.

To eliminate one common source of confusion, I’ve decided to begin versioning Highslide JS .NET based on the version of Highslide JS embedded within the the control. For example, since this release is v4.1.4, it contains v4.1.4 of Highslide.

Changes in v4.1.4 include:

  • Updated embedded Highslide JS script version to 4.1.4. You can see what has changed in that on the Highslide.com changelog page.
  • Added ControlBarPosition property to the HighslideManager, which allows you to position the enlargement’s control bar in any corner of the image.
  • Added several properties (ControlBarPreviousTitle, ControlBarNextTitle, ControlBarMoveTitle, and ControlBarCloseTitle) to control title attributes of links rendered in the control bar. Useful for localization.

As always, the free download is available on the Highslide JS .NET project page.

What ASP.NET developers should know about jQuery

AJAX, ASP.NET, JavaScript, jQuery By . Updated May 19, 2011

As much as I enjoyed attending MIX09 this year, it wasn’t a difficult decision when Karsten asked me to write an article for the MIX Online site.

Reading this here, there’s a good chance the article is targeted below the amount of jQuery expertise you already have. However, it’s been brought to my attention that some readers have found it useful for sending to their more JavaScript-phobic coworkers.

So, I decided that it’s worth mentioning here after all:

It’s hard to believe that JavaScript is already well over a decade old. Often relegated to marginal tasks in its early years, JavaScript has grown to become a pillar of modern web development. With the current popularity of DHTML and AJAX, it can be difficult to find a site that doesn’t use JavaScript anymore. One of the driving forces behind JavaScript’s newfound popularity is a proliferation of JavaScript frameworks, such as jQuery.



Click here to continue reading this article on the MIX Online site »

How I handle JSON dates returned by ASP.NET AJAX

AJAX, ASP.NET, JavaScript, jQuery By . Updated May 1, 2009

A calendar

The problem of how to handle dates in JSON is one of the more troublesome issues that may arise when directly calling ASP.NET AJAX web services and page methods.

Unlike every other data type in the language, JavaScript offers no declarative method for expressing a Date. Consequently, embedding them within JSON requires a bit of fancy footwork. Since the question of how I handle this problem is something asked often in emails and in comments on other posts here, I want to address the topic with its own post.

To that end, I will attempt to explain what exactly the problem is with dates in JSON, how ASP.NET AJAX solves it, and my alternative solution that I believe is easier and works just as well in most cases.

Click here to read the rest of this post »

Using complex types to make calling services less… complex

AJAX, ASP.NET, JavaScript, jQuery By . Updated June 6, 2009

So far, my examples of using jQuery to interact with ASP.NET AJAX services have avoided passing complex data to the server during the request. This has been intentional, because I didn’t want to over-complicate the examples.

For primarily read-only scenarios, like the RSS reader examples, passing just a few simple values to the service is often all you need. However, this scalar approach quickly becomes untenable when making real-world service calls.

In this post, I’m going to show you how passing complex types to the server helps alleviate complexity, how json2.js and a data transfer object (DTO) facilitates this, and how to use jQuery to very easily build the DTO.

Click here to read the rest of this post »

PostBack Ritalin v1.0

AJAX, ASP.NET, PostBack Ritalin, UI By . Posted April 6, 2009

Thanks to all of your excellent feedback during the months since the last release of PostBack Ritalin, an improved version is ready for release today. With the addition of “disable all elements”, I believe the control is now feature complete, worthy of a version 1.0 release.

Notable changes in v1.0 include:

  • Added disable all elements functionality to MonitoredUpdatePanels.
  • Fixed a bug in the WaitImage preloading functionality, that prevented the MonitoredUpdatePanels’ WaitImages from being preloaded.
  • Added both debug and release versions of the JavaScript resource. Your site’s compilation mode will determine which script version is embedded.
  • Fixed a problem handling postbacks raised by Button controls that have their UseSubmitBehavior property set to false.
  • Improved ClientID handling in naming containers.

As always, you can visit the PostBack Ritalin project page to download the latest version, see usage examples, and find documentation.

$(document).ready() and pageLoad() are not the same!

AJAX, ASP.NET, JavaScript, jQuery By . Posted March 25, 2009

Recently, I’ve attended several presentations in which ASP.NET AJAX’s pageLoad() shortcut is demonstrated as interchangeable with jQuery’s $(document).ready() event. The suggestion that both methods are equivalent actually appears to be true in simple demos, but is not the case and is certain to lead to later confusion.

While they seem similar on the surface, $(document).ready() and pageLoad() are very different behind the scenes. Determining the earliest point that it’s safe to modify the DOM requires a bit of black magic, and the two libraries approach that in their own unique ways. Additionally, pageLoad() is overloaded with some extra functionality which may surprise you.

In this post, I’ll clarify the major differences between jQuery and ASP.NET AJAX’s initialization functions, what implications those difference have in practice, and show you a third alternative when working with ASP.NET AJAX.

Click here to read the rest of this post »

Use jQuery to catch and display ASP.NET AJAX service errors

AJAX, ASP.NET, jQuery, UI By . Posted March 4, 2009

Another user fed up with your lack of error handling!

If you don’t properly handle the inevitable errors in your web applications, you can expect your users to eventually react about like this guy. Since they typically squelch any server-side errors, AJAX service calls are especially problematic. In fact, they rarely even throw a client-side error when they fail.

Even when a client-side error is thrown, most users won’t notice it and the ones who do notice won’t know what the error means or what to do next. In fact, I’ve found that even many developers don’t notice client-side scripting errors that occur while they’re debugging their own applications!

To help you remedy this problem in your own applications, I want to show you one way that I handle AJAX service call errors with jQuery. To do this, we will build an error-prone web service, make an AJAX request to it via jQuery, handle the resulting server-side errors gracefully, and use a jQuery plugin to attractively present those errors.

Click here to read the rest of this post »

A breaking change between versions of ASP.NET AJAX

AJAX, ASP.NET, JavaScript, jQuery By . Posted February 10, 2009

When working directly with JSON serialized ASMX services, be it via jQuery, pure XmlHttpRequest calls, or anything else other than the ScriptManager, one question inevitably arises. That question is of the inexplicable .d attribute that appeared in ASP.NET 3.5.

What is it? Why is it there?

In this post, I’ll use both a 2.0 and a 3.5 example ASMX web service to illustrate exactly what’s going on. I’ll also show you why it’s a good change.

Click here to read the rest of this post »

How to rotate JavaScript ads during ASP.NET AJAX requests

AJAX, ASP.NET, JavaScript, UI By . Updated January 8, 2009

A common question that I find myself fielding lately is how to handle the problem of rotating JavaScript based advertisements. As AJAX becomes ubiquitous on ad supported sites, we must take care that decreasing page views don’t also mean proportionally decreasing revenues.

Many find their way to ScriptManager.RegisterStartupScript, use that to re-inject the script during a partial postback, and expect that doing so will refresh the ad. Unfortunately, that doesn’t work when dealing with JavaScript based ads such as Google’s AdSense.

In this post, I’m going to show you why RegisterStartupScript does not solve the problem, the alternative that I suggest, and how to use that method to also defer loading of advertisements until after your content.

Click here to read the rest of this post »