YUI Sparkline Widget « Chicken of the Web

YUI Sparkline Widget « Chicken of the Web

If your into cutting edge, this is a nice example of subclassing YUI 2.7 charts to create sparklines in <canvas> and javascript.

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YUI 3: Design Goals and Architecture -Satyen Desai » Garuna Web Designer

YUI 3: Design Goals and Architecture -Satyen Desai » Garuna Web Designer

Satyen Desai goes over lessones learned from YUI 2.7, and the design goals for YUI3. YUI 2 users have expressed the need for more from YUI3

1. Lighter
1. Finer Granularity
2. Code reuse, common base class, easier to create plugins and extensions
2. Easier
1. Conistant API
   
1. Selector, Widget class, Base
2. Convenience - each, bind, chaining, syntax sugar
3. Faster
1. Opportunity to re-factor performance (drag and drop etc)

These are all valid points. In YUI 2, if I want to use a specific util or widget, I would get alot of code that I really didn't need all the time. In YUI 3 you get the option to only include parts of the components you need. This makes sense when building plugins, and widgets of your own, as well as how the core objects relate. A Tooltip widget for instance does not need all the code for an Overlay or dialog box even though they may use some of the same code for making shims or floating elements.

Satyen also goes over application instances with YUI().use() and how it is protected, and self populating. For exmaple YUI().use("anim") will attach optimal dependencies for the anim library, and attach anim to Y. var $anim = new Y.Anim(). This version of anim is garunteed to be the version of the library you are working with, and will never conflict with other widgets on the page.

The custom event handling in YUI 3 has grown quite mature with Event Facades for Dom events and Custom events. 

Custom Events:

slider.on('valueChange', function(e){
  if(e.newVal < 200) {
     alert("New Value " + e.newVal + " is less than 200");
  } 
});

Over all this is a wonderful introduction in getting developers up to speed with the changes from YUI 2 to YUI 3.

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Using Prototype and YUI

Using prototype and YUI

There are many reasons why you might use prototype.js with yui. You may be moving to Yahoo User Interface, or vice versa, or you may just prefer some flexibility. Whatever the reason, there are some good points to using the two together. I have pointed out several times on this blog and Practical Prototype that I personally prefer this method. I use YUI for the widgets, and use prototype for setting up classes, events, and other low level organization. Let's see a quick example:

MySimpleDialog = Class.create({
  initialize: function($div_id, $options){
    this.defaults = {
      width: "20em",
      fixedcenter: true,
      visible: false,
      draggable: true
    };
    Object.extend(this.defaults, $options || {});
    this.dialog = new YAHOO.widget.SimpleDialog($div_id, this.defaults);
   
  },
 
  render: this.dialog.render,
  show: this.dialog.show,

  setTitle: function($title){ this.dialog.setHeader($title);}
  setBody: function($body){ this.dialog.setBody($body); }
});

To initialize a new MySimpleDialog all we have to do now is:

var $mydialog = new MySimpleDailog('my div id');

Notice we do not have to send any options to the SimpleDialog constructor, and if we had, they would override the defaults. To get Fancy, we could create a Template class to be used by our "overridden" setBody method. Keeping things generic helps you to reuse scripts.

Y.get() != new Element()

While trying to use YUI 3.0, I was attracted to try out the YUI Node feature with the following code

$ele = Y.get('foo');

I was working out some race condition problems, and was hoping the waiting feature (where YUI will wait for the element to be in a ready state) would solve some problems for me.

What I had forgot was that Y.get is not the standard dollar function ( $('foo'), $('#foo'), etc ). This poses some real problems for me. I didn't really used the Dom.get methods, and probably for the same reasons, as I use both YUI and prototype together mostly.

But now I want to integrate the really nice features of YUI 3 into my code, and try and break away from my prototype "crutch". However, since I do use other 3rd party libraries for various things, most of them rely on straight up Dom elements being passed to them.

I hate to say it, but I have found something in YUI that just does not sit well with me.

The code still seemed to work with

Y.get('foo');
$ele = $('foo');

But I can't say for sure, and this seems pretty hacky?

YUI 3.0.0 beta 1

YUI 3.0.0 beta 1 is now available for download from YUILibrary.com.

From the Yahoo! User Interface Blog:

"This release takes YUI 3 out of its preview phase and brings its APIs to a near-final state. For those intending to implement YUI 3, the 3.0.0 beta 1 release is a good place to begin the transition. If you’ve been working with the latest preview release, George Puckett has provided a comprehensive 3.0.0 beta 1 changelog to guide you. We look forward to hearing your feedback as you begin working with 3.0.0 beta 1, and we’ll work hard to address that feedback as we prepare for a GA release in the coming months."


Some very interesting things made this release

"StyleSheet: StyleSheet makes it easy to create and modify CSS rules on the fly, allowing you to dynamically style page elements with fewer repaints."

Add stylesheets dynamically!


"ImageLoader: ImageLoader allows you to defer the loading of images that aren’t in the viewport when the page paints, throttling bandwidth usage and improving performance"

Images won't load until they enter the viewport, for longer pages, or hidden elements this is pretty huge. The bandwidth savings could be worth it.

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YUI 3 Preview Release 2 - IO

Today I will go over the new IO Utility in the YUI 3 Preview Release 2

"IO is an HTTP utility that enables HTTP requests while maintaining a persistent client UI, for the purpose of data retrieval and content update. IO uses the XMLHttpRequest object for making "same-domain" requests. IO can make "cross-domain" requests, when instructed to do so, using an alternate HTTP transport."


What does this mean really? This means we have a single, consistent, interface to various data sources we may point our UI at. This data may be from our site, or another data provider on a different site. When the data resides on our site IO will use XHR (XMLHttpRequest ) to request the data, standard "AJax". When we are making our request cross-domain, the IO utility will use a flash swf to make the call, along with a crossdomain.xml (to let the flash know which sites it has access to). The crossdomain.xml is fairly important on a https: site as IE will complain to no end that you are trying to access non secure data, or mixing secure with non-secure.  The crossdomain.xml resides in your document root.

So, let's see what the YUI 3 team has given us. The basic example provided at the IO Utility page sets up the use of io-base, defines a completed function, and subscribes to the event. The key here seems to be subscribing to the event :

// Subscribe to event "io:complete", and pass an array
// as an argument to the event handler "complete". Since
// "complete" is global.
// At this point in the transaction lifecycle, success or
// failure is not yet know.
Y.on('io:complete', complete, this, ['lorem', 'ipsum']);

When the Y.io(uri) event "complete" finishes, we want to run "complete" function with "this" as the context of execution, and pass also an array ['lorem', 'ipsum']

This may be quite different and confusing to just about every other Framework out there. But so much better! There are a few posts on nabble where people are asking why the IO isn't "seperate" for each request, and the answer lies above. IO is a presistant connection, and it has a context that it runs in. If you are specifying IO in the global context, then all your requests are going to be in the global context, which is specified by "this".

In other words, Event handlers run in thier own context, so you could have multiple listeners on the io:complete event, but only some would run depending on context:    Therefore, you could register a GlobalEvents object and set that context, just as in the examples and this would run for every IO request. If however, you have objects with different scopes, the global would fire as well as the callbacks in different scopes that are set to listen for io:complete.  

The new IO utility also offers a "queue" which you can start, stop, promote, purge, and set the size. This is a big step in ajax frameworks as most like prototype do not come with these capabilities built in. With a queue you can send transactions and gracefully monitor and manage them with the io events and queue commands.

One way I can see this being very useful is if you had created a queue on page onload to load various items not immediatly visible to the user. But say the user then clicks on one of the items, we can immediatly stop the queue, and promote that request to the top of the queue, and when that completes, continue with the loading of the rest of the items! This is, to say the lease, very useful.