Today I’m going to start a three part tutorial in implementing a custom datagrid with prototype & scriptaculous. In part 1 we’ll explore the html & css underlying the widget. Parts 2 & 3 will look at interactivity and legacy browser support (IE 6).

Disclaimer: this project is designed to work on IE 7 and later. It will not render properly on IE 6. We will look into that more with part 3.

So it starts with a table. Tables are much maligned nowadays. The focus is on semantic markup and creative uses of <div> and <span>. In the energy behind css layouts over the past few years, the new markup elements available to the venerable table have been slightly overlooked. Sure the reign of table based layouts is over, but tables are now able to display data more semantically and style it more simply than ever before.

Here’s a traditional HTML table to start from.

<table>
<tr><td> Item Number</td><td>Description</td><td>Qty</td><td>Unit Price</td><td>Total Price</td></tr>
<tr><td>0023</td><td> Apples</td><td>3</td><td>.56</td><td>1.68</td></tr>
<tr><td>0057</td><td> Pears</td><td>13</td><td>.74</td><td>9.62</td></tr>
<tr><td>0137</td><td> Bananas</td><td>8</td><td>.31</td><td>2.48</td></tr>
<tr><td>0587</td><td> Kumquats</td><td>17</td><td>.26</td><td>4.42</td></tr>
<tr><td>0054</td><td> Oranges</td><td>3</td><td>.45</td><td>1.35</td></tr>
<tr><td></td><td>Total</td><td>44</td><td></td><td>19.55</td></tr>
</table>

It’s a decent start, but we can do better. First lets separate the body from the head with <thead> & <tbody> tags. We’ll also replace the header cells with <th> tags to denote their importance. We’re also going to add a set of row numbers. We’ll use <th> for these as well to signify that they aren’t really part of the data (note the empty <th/> we added to the header to make everything stay consistent).

<table>
<thead>
<tr><th /><th> Item Number</th><th>Description</th><th>Qty</th><th>Unit Price</th><th>Total Price</th></tr>
</thead><tbody>
<tr><th>1</th><td>0023</td><td> Apples</td><td>3</td><td>.56</td><td>1.68</td></tr>
<tr><th>2</th><td>0057</td><td> Pears</td><td>13</td><td>.74</td><td>9.62</td></tr>
<tr><th>3</th><td>0137</td><td> Bananas</td><td>8</td><td>.31</td><td>2.48</td></tr>
<tr><th>4</th><td>0587</td><td> Kumquats</td><td>17</td><td>.26</td><td>4.42</td></tr>
<tr><th>5</th><td>0054</td><td> Oranges</td><td>3</td><td>.45</td><td>1.35</td></tr>
<tr><td></td><td>Total</td><td>44</td><td></td><td>19.55</td></tr>
</tbody></table>

The <thead> specifies the header content. When printed, a browser should print it on every page the table spans. More importantly for us, it is a unique dom node we can grab for styling instructions. <tbody> works in a similar way, It allows us to break the internals of a table into a set of segments. This will come in handy later. <th> is a different beast entirely. I like to think of it as the ying to <td>’s yang. <th> & <td> are to <table> what <dt> & <dd> are to <dl>: a semantic way to denote name / value pairs.

Now that our table has a header and a body, It’s time to give it a footer. We’ll do this by using the <tfoot> tag.

At first glance, there is visually no difference between the 2nd and 3rd examples. Both of them look identical. The source, tells a different story. In the 3rd example, the footer row is actually ahead of the <tbody> in the source. This is the beauty of <tfoot> It lets us place the footer early in the table and cleanly separate it from the tbody that follows. It also guarantees that the <tfoot> appears last no matter what we append to the table via script.

All of this looks good, except it would be great if the columns were better styled.  The two columns with financial data especially should be aligned left to ensure that the decimal points align.  In a perfect world, we’d be able to do this with column groups, but that’s something for part 2.

I’m a javascript harlot and proud of it.  I espouse no allegiance to any particular framework, widget or philosophy and pride myself n my ability to select the best tools for the job based on a project’s unique constraints.  I find this puts me in a slightly unique position among developers.  I don’t carry the deep and intimate details of the framework in my brain, instead I prefer to maintain a much shallower depth of understanding.  I prefer road maps and traffic advisories to in depth aboriginal understanding.

This is why I was affected so severely by what seems to superficially be a minor inconvenience: the Scriptaculous wiki outage.  Scriptaculous has already lagged behind prototype in its depth of documentation.  This makes sense, after all, much of the heavy lifting and complex API’s are handled by prototype so an extensive documentation isn’t really necessary.  For most developers, a few well executed demo implementations of the key features are all we need to get the job done.  In fact, well executed demo implementations are especially critical for a framework like scriptaculous where many of the key features require complex implementation and are likely to be only used once or twice per project and not necessarily referenced day in and day out as the project comes together.

Last week, I was tasked to work on just such a feature.  We new the type ahead find was straightforward to implement given the Scriptaculous documentation.  We also knew that it was fundamentally gravy.  Sure, the feature was important to the end product and would mean much of the difference between user frustration and adoption, but It was also significantly less important than some other items like successfully storing to the database, authentication and form processing.  In short, we put it off to the end as I’m sure many developers would.

Unfortunately, the documentation was gone when we needed it.  The wiki outage had hosed the Scriptaculous hosted media wiki instance and the page we needed was simply missing from the new system.  During a several minute minor panic we tried the various internet archives and similar sites in a desperate attempt to find a new solution with negligible success.  Eventually we found the documentation we needed.  

To Scriptaculous’s credit it was in a surprisingly logical place and well done.  Turns out that scriptaculous has wonderful self documentation as part of the functional tests / unit tests suite.  These test files provided us with solid demonstrations of features we were looking to use for this project.

There’s no doubt in my mind that a software component’s single biggest asset is its documentation.    This is as much a feature as an ultra-fast query selector or smoothly transitioning widget.  Scriptaculous provides powerful documentation in a slightly unlikely place but doesn’t provide decent bread crumbs to its existence from the frameworks public site. Given the critical nature of such documentation, It would be nice if it integrated in to the public site or atleast minimally referenced as a resource.

I’m always looking for ways to improve my javascript development and after a few weeks of playing, Javascript MVC test looks like it might be one the best tools yet.

We all know the power of testing our code.  A proper suite of unit tests can be among a projects most valuable assets.  They can ensure against the regressions rampant in rapid application development cycles that may not have adequate opportunities for proper QA.  Most importantly, when coupled with continuous integration tools, a comprehensive test suite catches many bugs close to when they are written and when they are easiest to correct.

Historically, testing javascript hasn’t been the most useful or productive of tasks.  The type of data manipulation, object inheritance and communication most conducive to unit testing has been minimized in most javascript applications.  Instead, most javascript is highly event driven and is often loosely tied to any specific server side data model.  Test MVC stands to provide a powerful testing framework for just those tasks we normally use javascript for.

Key Features

• Cross browser¹ support for typical DOM events, like keypress, click, submit, blur, and focus
• Simulate writing text or dragging an element
• Easily simulate AJAX functionality with sample data in fixture files