Head first into javascript (and jQuery)

So, I had to take a break from doing the Code Katas just as I was getting to the really cool one about Bloom Filters. The reason for the unexpected break from kata-ing was that I had a project thrown into my lap. I say “project” not because it was some huge thing that needed doing — lots of people reading this could probably have done it in a matter of a few hours — but because it involved two things I’ve never done any real work with: javascript, and jQuery.

My task? Well, first I had to recreate a page from a graphic designer’s mockup. So, take a JPEG image and create the CSS and stuff to make that happen. Already I’m out of my comfort zone, because historically I’m a back-end developer more comfortable with threading than CSS (95% of my code is written in Python and is daemonized/threaded/multiprocess/all-of-the-above or worse), but at least I’ve done enough CSS to get by.

Once the CSS was done, I was informed that I’d now need to take the tabular reporting table I just created and make it sort on any of the columns, get the data via AJAX calls to a flat file that would store the JSON for the dummy data, create nice drop-down date pickers so date ranges in the report could be chosen by the end user, page the data using a flickr-style pager so only 20 lines would show up on a page, and alternate the row colors in the table (and make sure that doesn’t break when you sort!).

How to learn javascript and/or jQuery REALLY fast

How exactly do you learn enough javascript and jQuery to get this done in a matter of a few days (counting from *after* the CSS part was done)? Here are some links you should keep handy if you have a situation like this arise:

  • If Douglas Crockford says it, listen. I’d advise you start here (part I of a 4-part intro to javascript). That site also has his ‘Advanced Javascript’ series. He also wrote a book, which is small enough to read quickly, and well done.
  • Packt has a lot of decent resources for jQuery. Specifically, this article helped me organize what I was doing in my head. The code itself had some rather glaring issues — you’re not going to cut-n-paste this code and deploy it to production, but coming from scorched earth, I really learned a lot.
  • After the project was already over I found this nice writeup that covers quick code snippets and demos illustrating some niceties like sliding panels and disappearing table rows and how to do them with jQuery.
  • jQuery itself has some pretty decent documentation for those times when your cut-n-pasted code looks a little suspect or you’re just sure there’s a better way. Easy to read and concise.

Why I Wrote My Own Sorting/Paging in jQuery

Inevitably, someone out there is wondering why I didn’t just use tablesorter and tablesorter.pager, or Flexigrid, or something like that. The answer, in a nutshell, is paging. Sorting and paging operations, I learned both by experience and in my reading, *NEED* to know about each other. If they don’t, you’ll get lots of weird results, like sorting on just one page (or, sorting on just one page until you click to another page, which will look as expected, and then click back), or pages with rows on them that are just plain wrong, or… the list goes on. This is precisely the problem that the integrated “all-sorting-all-paging” tools like tablesorter try to solve. The issue is that I could not find a SINGLE ONE that did not have a narrow definition of what a pager was, and what it looked like.

I wanted (well, I was required to mimic the mockup, so “needed”) a flickr-style pager — modified. I needed to have each page of the report represented at the bottom of the report table by a block with the proper number in the block. The block would be clickable, and clicking it would show the corresponding page of data. This is more or less what Flickr does, but I didn’t need the “previous” and “next” buttons, and I didn’t need the “…” they use (rather effectively) to cut down on the number of required pager elements. So… just some blocks with page numbers. That’s it.

I started out using tablesorter for jQuery, and it worked great — it does the sorting for you, manages the alternating row colors, and is a pretty flexible sorter. Then I got to the paging part, and things went South pretty fast. While tablesorter.pager has a ‘moveToPage’ function, it’s not exposed so you can bind it to a CSS selector like the ‘moveToPrevious’, ‘moveToLast’, ‘moveToNext’ and other functions are. So, I tried to hack it into the pager code myself. I got weird results (though I feel more confident about approaching that now than I did even three days ago). There wasn’t any obvious way to do anything but give the user *only* first/last/previous/next buttons to control the paging. I moved on. I googled, I asked on jQuery IRC, I even wrote the developer of tablesorter. I got nothing.

I looked at 4 or 5 different tools, and was shocked to find the same thing! I didn’t go digging into the code of all of them, but their documentation all seemed to be in some kind of weird denial about the existence of flickr-style paging altogether!

So, I wrote my own. It wasn’t all that difficult, really. The code that worked was only slightly different from the code I’d fought with early on in the process. It just took some reading to get some of the basic tricks of the trade under my belt, and I got a tip or two from one of the gurus at work as well, and I was off to the races!

Lessons Learned

So, one thing I have to say for my boss is that he knows better than to throw *all* of those things at me at once. Had he come to me and said he wanted an uber-ajaxian reporting interface from outer space from the get-go, I might not have responded even as positively as I did (and I would rate my response as ‘tepid, but attempting a positive outlook’) . It’s best to draw me in slowly, a task at a time, so I can get some sense of accomplishment and some feedback along the way instead of feeling like I still have this mountain to climb before it’s over.

I certainly learned that this javascript and jQuery (and AJAX) stuff isn’t really black magic. Once you get your hands dirty with it it’s kinda fun. I still don’t ever want to become a front end developer on a full-time basis (browser testing is where I *really* have zero patience, either for myself or the browsers), but this experience will serve me well in making my own projects a little prettier and slicker, and nicer to use. It’ll also help me understand more about what the front end folks are dealing with, since there’s tons of javascript at myYearbook.

So, I hope this post keeps some back end scalability engineer’s face from turning white when they’re given a front-end AJAX project to do. If you’ve ever had a similar situation happen to you (not necessarily related to javascript, but other technologies you didn’t know until you were thrown into a project), let’s hear the war stories!!

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  • Jason

    Just curious if you looked at the jQuery DataTables plug-in, and if so, if it had the same sorting/paging issues as the other tools.

  • m0j0

    I’m pretty sure that DataTables *was* one of the things I looked at, but I don’t remember if it was the pager specifically that made me look elsewhere. I’m inclined to think that it was.

  • Ken

    Doh, hit the reply button before mentioning that the Douglas Crockford video linked above has been taken down. You can find it and many other js/yui videos at http://developer.yahoo.com/yui/theater/.

  • PeterH

    @Ken wrote that the Doug C video had been taken down, but clicking on the original link brings it up just fine today.