Use jQuery and ASP.NET AJAX to build a client side Repeater

AJAX, ASP.NET, JavaScript, UI, jQuery By Dave Ward on June 26th, 2008

There was some interesting discussion on Matt Berseth’s blog recently, regarding methods for building and displaying markup on the client side. Though I haven’t posted any examples here before, rendering markup on the client is a technique that I use often and recommend.

By sending only data to the client, you can profoundly reduce the size of what you send and see a substantial increase in performance. You also allow yourself the ability to easily add features like light-weight sorting and paging on the client. This can not only improve your users’ experience, but reduce server load and bandwidth requirements.

To that end, I’m going to walk you through these four steps to effectively implementing a client side Repeater, using ASP.NET AJAX and jQuery:

  • Create an RSS Reader page method to return JSON data to the client.
  • Call that page method with jQuery.
  • Use the returned data to build a table on the client side.
  • Improve upon the table creation with a templating plugin.

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3 mistakes to avoid when using jQuery with ASP.NET AJAX

AJAX, ASP.NET, JavaScript, jQuery By Dave Ward on June 5th, 2008

Over the past few weeks, I think I have definitely embodied Jeff Atwood’s claim that we’re all amateurs, learning together. Despite my best efforts to thoroughly test before posting, a few problems slipped through in my recent posts about using jQuery to consume ASP.NET JSON serialized web services and using jQuery to call ASP.NET AJAX page methods.

On the bright side, your great feedback in both posts’ comments has reinforced the fact that some of the best content on my blog is the part that you write.

In this post, I’m going to detail three of the problems that were discovered as a result of those previous two posts:

  • An extra requirement when making a read-only request to IIS6+.
  • An oddity in Internet Explorer 7’s XmlHttpRequest class.
  • A common mistake when passing JSON parameters through jQuery.

Finally, I’ll suggest what I now believe to be a best practice usage, taking all of these issues into account.

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Using jQuery to directly call ASP.NET AJAX page methods

AJAX, ASP.NET, JavaScript, jQuery By Dave Ward on May 29th, 2008

When it comes to lightweight client-side communication, I’ve noticed that many of you prefer ASP.NET AJAX’s page methods to full ASMX web services. In fact, page methods came up in the very first comment on my article about using jQuery to consume ASMX web services.

Given their popularity, I’d like to give them their due attention. As a result of Justin’s question in those comments, I discovered that you can call page methods via jQuery. In fact, it turns out that you can even do it without involving the ScriptManager at all.

In this post, I will clarify exactly what is and isn’t necessary in order to use page methods. Then, I’ll show you how to use jQuery to call a page method without using the ScriptManager.

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Inline Edit Box on CodePlex and new PostBack Ritalin beta

AJAX, ASP.NET, PostBack Ritalin, UI By Dave Ward on May 16th, 2008

I’ve decided to open source Mike Davis’ ever-popular Inline Edit Box .NET control. Neither of us have enough time to maintain it properly, and several of you have expressed interest in contributing if it were open source. So, its new home is CodePlex: http://www.codeplex.com/InlineEditBox

You’ll have to bear with me, because this is my first CodePlex project and I’m still familiarizing myself with the admin functionality of the site. If you have any trouble contributing to the project, contact me directly and I’ll do my best to resolve it quickly.

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Highslide JS .NET Updated (v0.7)

AJAX, ASP.NET, Highslide, UI By Dave Ward on April 29th, 2008

An update to Highslide JS .NET is available today. I recommend that everyone upgrade, to benefit from the memory leak fixes in the latest Highslide JS.

v0.7 (4/29/2008)

  • Updated embedded Highslide version to 3.3.17.
  • Improved caption rendering, using inline caption divs. This should result in more semantic markup, pairing your captions with your images.
  • Added HighslideManager property: NumberOfImagesToPreload. This allows you to control how many images are automatically preloaded.
  • Added HighslideManager property: FadeInOut. When true, this fades the enlargement in and out as it’s resizing.
  • Added HighslideManager property: RenderScriptInPlace. This allows you to control where on the page the Highslide JS script is inserted in your page.
  • Updated download to include a sample site, to make it a little easier to get up and running quickly.

As always, the latest version is available on the Highslide JS .NET project page.

Why you should not place your whole site in an UpdatePanel

AJAX, ASP.NET, Performance, UI By Dave Ward on April 23rd, 2008

Perhaps due to its ubiquitous presence in web based email services, implementing asynchronous site navigation is frequently a design requirement when building AJAX based sites. Unfortunately, the also ubiquitous UpdatePanel is chosen to accomplish this far too often.

I’d like to take a moment to strongly recommend against doing that.

I’m going to explain what I believe are the three most dangerous drawbacks inherent to UpdatePanel based navigation: Performance degradation, usability concerns, and lack of maintainability.

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Why do ASP.NET AJAX page methods have to be static?

AJAX, ASP.NET, OO By Dave Ward on April 16th, 2008

Image of a spark (static).Dozens of variations on the title of this post are some of the most common searches that bring people here to Encosia. Unfortunately, the search engines all point to a post that doesn’t answer the question. It’s also a frequent question raised on the ASP.NET message boards, typically without a satisfactory answer provided.

However, it is an important question, the answer to which is important to understand. So, in an attempt to fill in this gap for the searchers and perhaps preemptively help others, I want to proceed to answer it as thoroughly as possible without overly complicating the whole business.

In order to do this, we’ll have to take a brief tour of WebForms, including:

  • Understanding what the Page class is, and why we have it.
  • One specific thing that the Page class does for us.
  • How this is accomplished, behind the scenes.
  • What the static keyword entails, when used with a method.
  • Finally, why page methods must be static.

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Using jQuery to Consume ASP.NET JSON Web Services

AJAX, ASP.NET, JavaScript, UI, jQuery By Dave Ward on March 27th, 2008

Animated example of the RSS feed block from this article. In response to many of the articles here, I receive feedback asking how to achieve the same results without using ASP.NET AJAX. As much as I’m a fan of ASP.NET AJAX, I must agree that its JavaScript payload can certainly be a drawback in some situations.

My recent deferred content loading post is an excellent example of that. I was using jQuery for presentational effects, and using a ScriptManager to call a web service. Loading the JavaScript for both frameworks was a bit counterproductive, since the whole point was to improve initial load time.

In this post, I intend to correct that.

First, I’ll cover the two requirements necessary when calling an ASMX web service that’s being JSON serialized by the ASP.NET AJAX extensions. Then, I’ll show you how to do this with jQuery. Finally, I’ll update the deferred content loading example accordingly.

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Why my ASP.NET AJAX forms are never submitted twice

AJAX, ASP.NET, JavaScript, UI By Dave Ward on March 4th, 2008

Animated example of the button disabling technique in this article.The overzealous double-clickers amongst our users often make it desirable to temporarily disable the controls that trigger server side processing. Previously, I’ve shown you how to disable a button during a postback, how to disable a button during a partial postback, and even written a server control to automate the latter.

However, what if you wanted to be more thorough and disable all of the buttons on a page?

In this post, I’m going to show you how to do just that. I’ll also show you how to disable only the buttons in the UpdatePanel raising the event. Finally, for the jQuery users out there, I’ll show you how to simplify the process down to one line of code.

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Boost ASP.NET performance with deferred content loading

AJAX, ASP.NET, JavaScript, Performance, UI By Dave Ward on February 5th, 2008

FireBug graph of net requests
When rolled into the page life cycle of an ASP.NET WebForm, that red bar is one of your application’s greatest enemies. No matter how well you optimize the rest of the page, even one slow task can become the sole factor determining a user’s perception of the entire page’s performance.

In this post, I’m going to show you one way to circumvent that problem. By placing ancillary content in user controls and delaying their load until the core page content has been displayed, you can drastically improve perceived performance.

When broken down into digestible chunks, the technique is easy to implement and lends your application a level of polish that your users are sure to appreciate. The four steps required to accomplish this will be: building the user control, statelessly rendering the control as HTML, providing progress indication, and using ASP.NET AJAX to request and inject that HTML.

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