JS Library Roundup

In Part III of the JavaScript Renaissance, we spent another long evening exploring Prototype, Script.aculo.us, and jQuery, and getting a feel for the scope and power of these popular DHTML/Ajax libraries. A good chunk of that time was spent hacking at the Firebug console and experimenting with live HTML documents for immediate feedback.

You can download the presentation here.

Thanks again to the Wheaton ex-Perl Mongers for coming out to learn a little more JavaScript. Come out and see the Perl Mongers reborn as the first arm of the new Polyglot Programmers group!

Addendum: Some of you at the presentation wanted to know to use Greasemonkey to import libraries into web pages after they've already been loaded. Here's the skinny:

• Go to https://addons.mozilla.org/en-US/firefox/addon/748 and add the Greasemonkey Firefox extension
• After you restart Firefox you should see the telltale monkey face icon down in the lower right corner of your browser window
• Right click on the monkey face and select "New User Script..."
• Give the new script an identifiable name like "load_prototype" or "load_jquery", a namespace (can be anything, I'm not entirely sure what it's even used for), and a list of URLs to include or exclude from running the script
• Configure a text editor to edit Greasemonkey scripts
• Finally, enter and save the script

Here's the script I used to load prototype and most of script.aculo.us. Obviously, you'll need to change the paths to point to the files where they're installed on your system. Paste this into your new Greasemonkey document below the comments:

window.addEventListener('load', function() {
    var head = document.getElementsByTagName('head')[0];
    var libs =
      [
       'file:///..../prototype.js',
       'file:///..../effects.js',
       'file:///..../dragdrop.js',
       'file:///..../builder.js'
       ];
    for (var i in libs) {
      var script = document.createElement('script');
      script.type = "text/javascript";
      script.src = libs[i];
      head.appendChild(script);
    }
  }, false);

That should be enough to get you started! Please hit me up if you have any questions.

More Mongering

The Perl Mongers were at it again on Tuesday night, going above and beyond the call of duty, slogging through snow and slush to listen to more JavaScript tidbits. This time, we explored how to use JavaScript to interact with the browser window and HTML document, monitor and handle user events, and make remote HTTP calls. We finished up with some lively discussion questions about JavaScript libraries and frameworks and how they compete, relate, and stack on top of one another; so I'll try to go more into that question in the near future.

But for now, you can find the slides and samples of the presentation here.

Advanced JavaScript: Not for the Faint of Heart

Thanks to the kind folks from Chicago Perl Mongers, who took two hours out of their busy lives last night to learn a little bit about the dark corners and esoterica of JavaScript.

Those who have only been exposed to procedural and class-based languages often find JavaScript's unique brand of functional programming rather unusual, if not downright confusing. Its lexical scoping and prototype chaining rules allow for some very powerful metaprogramming facilities; but the language is finicky, and the very features that provide so much power can also be badly abused and hacked. It seems fair to say that this has been the rule, rather than the exception, until the dawn of the Ajax revolution in 2005. Did you know that you can easily create arbitrarily deep inheritance hierarchies in JavaScript, even though the language has no concept of classes? Create higher-order functions that can bind or curry parameters to existing functions? Extend language and DOM data types with custom functionality?

The future seems a lot brighter now, thanks to the tireless work of folks like Douglas Crockford, Dean Edwards, and John Resig, and to cross-browser JavaScript libraries like Prototype, jQuery, and Base.

The JavaScript Renaissance, Part I: The Core Language
Presentation
Snippets