QueryTemplates development progress

QueryTemplates 1.0 Beta3 is out since a week or so and next release is around the corner, so i decided to do some wrap-up of latest facts in library development:

• Extended data targets are no supported by all methods. This means each method can be re-targeted with jQuery insert methods like for example varsToSelectorBefore or even varsToSelectorAttr.
• New codeTo method type. It simply injects code groups. Idea evolved from methodTo approach, which would inject method calls. I find codeTo amuch more flexible and useful, but it can be less readable.
• New valuesToLoop method. In opposite to varsToLoop aka loop(), it will iterate existing data over DOM structure and commit it right away. This has less purpose on server side (but can be useful), but it’s essential on the client-side when you don’t want to make a server request.
• New conditional chains methods – onlyJS() and onlyPHP(). They allow to highly customize template for certain language. For example, everything between onlyPHP() and endOnly() will be applied only to PHP template, even when the same chain is used to create JS template.
• Light version for JavaScript is available. It contains all valuesTo methods which includes valuesToSelector, valuesToStack and valuesToLoop. Form methods and mutation events support will be next. It’s a jQuery plugin and demo is available.
• formFromVars will generate full form templates from structure and variable informations. Such form supports error messages and default values. Of course input-wrapper template is customizable. As for today there are couple of things to be done in this area and formFromValues will also be available soon.
• Syntax reference is complete. Each method has it’s own wiki page with 6-part example: markup, data, formula aka code, template, tree dump before and tree dump after. Also, new JavaScript Light version is included in this reference. User comment are allowed. Personally i think it’s the best part of project’s page ;)
• Some API refactorings had taken place. Old names are still accessible, but marked as deprecated.
  • varsFrom type was created from such methods as saveTextAsVar, saveAsVar, valuesToVars.
  • loop, loopOne and loopSeparate now becomes varsToLoop, varsToLoopFirst and varsToLoopSeparate and are grouped in ToLoop type.
• dumpTree is now more verbose and can be used both via HTML and plain text. Just do ->dumpTree() anywhere in the chain to see readable representation of selected structure. It’s used for syntax reference examples.

As you can see project is quite close to 1.0 final. Code seems stable and each method has pseudo-unit-test in form of example available in Syntax reference, which is generated as a real template. I just can’t wait to start implementing CSS interface i wrote before. Additionaly, as JavaScript version is out, there can be some use for jQueryServer.

Can CSS stylesheets be applied on the server-side ?

The question is: can CSS stylesheet be applied in the server-side ? And if yes, would would be the purpose ? I should say yes, they can and i would explain how and why. So what for are stylesheets ? “Applying cascading styles onto the DOM” may be the answer. But i would focus more on that why actually stylesheets are used for such purpose?

• Because they are clean ?
• Because CSS selectors do so much job, that besides them only really needed things are simple properties with obligatory number of arguments ?
• Because cascading inheritance is just right for the DOM ?
• CSS selector are simply benefiting from DOM structure’s nature

So first thing which needs to be implemented on the server is the DOM. When we already got it, so we can query it thou selector, that’s the first half. Now the properties. What could be the property on the server ? border-color ? Rather not. Do we need to style the DOM on the server ? Is it shown anywhere ? Not right now. On the server, page’s DOM is being build. Typically by various ways of string concatenation.

So if we need to build a DOM and same time we can query it with selectors, then the style’s properties should build / modify it’s structure. For example, show some articles or blog posts on the page. So here is pure CSS parser-validable code with some proposed server properties.

.section.articles ul > li {
  /* loop "articles" variable as "article" using "num" as index
  after that remove all other-than-first LIs */
  loop-one: articles num article;

  /* apply filter method on next variable output */
  vars-filter: htmlentities;

  /* use "article" fields and populate them inside nodes
  matched by ".a-%k" where %k is field name, eg .a-title */
  vars-to-selector: articles var(articleFields) null ".a-%k";

  /* example custom method to adding class for 1st loop node using index "num" */
  add-class-to-first: num custom-class;
}
/* show .comments node if variable articleComments is true */
.comments {
  if-var: articleComments;
}
/* bubbled event */
.section.articles:inserted {
  /* another custom method */
  /* null means 0 arguments */
  strip-tables: null;
}

So what have we done here ?

1. We simply build articles loop which prints it’s contents into proper child nodes automagically. It could have 3 fields or 345, but line in CSS is only one.
2. We’ve also used a custom method do add class basing on the loop position.
3. Comments presentance is conditional.
4. One Mutation Event is used. Hidden in :insert pseudoclass, really named DOMNodeInserted will apply on all new nodes which matches prior selector and were just inserted into the DOM structure.
5. Each unspecified event defaults to :load.

All properties should be simply methods which applies something on all matched nodes. Sound familiar ? That’s exactly what many of jQuery methods are doing. Take a look:

.section.articles {
  remove-class: section;
  attr: rel section;
  /* all css properties can be used
  but will result in inline "style" attributes */
  css: padding 2px;
}
/* this rule applies to all load-time nodes
and the new one too */
.change-me,
.change-me:inserted {
  text: "changed innerText";
  prepend: "
<div>changed</div>
";
  remove-class: change-me;
  /* reallocation, interesting... */
  insert-into: ".content";
  /* passing some data to forward ? */
  data: some-flag "some value for developer";
}

All from above properties are jQuery methods. Possibilities are huge. But let’s stick with simple things right now. How would it benefit ? Who will write those server-css-sheets ? I should say…

Utilizing Mutation Events for automatic and persistent event attaching

Most of you probably heard about Event Delegation, a technique where you bind to event of interest on parent node and when triggered event bubbles from child node, action in taken inside the parent. This pattern is widely popularized by reglib and Live Query (plugin for jQuery). Newly released jQuery 1.3 has it’s own implementation thou $.live() method.

This patten has couple of advantages over classic attaching model. First, it’s faster for BIG number of (same) nodes. Secondly, which is most important i think, it allows easy content exchange via AJAX. But with all that it has also disadvantages and main is that you doesn’t really attach to a node, only to it’s parent. That means when you relocate node in the DOM it looses it’s behavior.

That’s why i’ve came with the idea of using Mutation Events to take best parts from both patterns. Mutation Events aren’t supported in IE, but i’ve rolled out some compatibility layer to target this problem. Works also with document fragment appends introduced in jQuery 1.3.

You can go straight to the demo, which was tested and works with:

• Firefox 3 and 2 linux
• IE6 SP2 win32
• Opera 9.63 linux
• Safari 3.6 win32
• Chrome 1.0 win32

First lets see main code:

function attachEvents(node) {
	// node is an optional callback for filter()
	// that applies rules only for new nodes
	node = node || '*';
	$('.container1 .trigger1').filter(node).click(function(e) {
		alert('mutation events work');
		e.preventDefault();
	});
}

This is simple, common function that applies behaviors to the document. The only major difference from other such functions is node parameter, used as callback for filter() method, which limits found nodes to interesting ones. Now the actual event bindings:

// node inserted into DOM
$(document).bind('DOMNodeInserted', function(e) {
	attachEvents(function(node){
		return !e.target.skipEventAttaching &&
			this == e.target
	});
});
// node removed from DOM
$(document).bind('DOMNodeRemoved', function(e) {
	// add information property, that node has been detached
	e.target.skipEventAttaching = true;
});

Here the magic happens ;) First handler fires up our event attaching function with callback for filter as a parameter. Callback will check if found node is target of the mutation event or is it reinserted. Second handler adds flag about reinserting.

You can see demo which compares this technique with jQuery 1.3 and reglib. It consists of 3 different implementation:

• jQuery 1.3 using Mutation Events
• jQuery 1.3 using $.live
• reglib

Test it like this: click add node (couple of times), click .trigger (first one, last one) then do move node and again click moved node. Each time when clicking on .trigger, one (and only one) alert should pop out saying that certain technique works.

Additionally there’s a IE compatibility for mutation events in conditional comment. Great help writing it was from ieproto example.

Of course this is proof-of-concept and souldn’t be used in production until fully tested and fixed.

$.include() – script inclusion jQuery plugin

Don’t like writing <script> tag for every new JS You need ? Nobody likes. Thats why i wrote $.include.

Use it like this:

$.include('js/my-script.js');

It’s similar plugin to that one written by Petko D. Petkov, but with couple of enhancements :

• Properly delayes onDomReady event
• Gives You control over order of loading scripts

Here is extended example:

$.include(
	// URL
	'js/my-script.js',
	// will be loaded after this script
	$.include(baseURL+'js/my-other-script.js')
);
$.include('js/src/behaviors.js',
	// dependencies can also be an array
	[
		$.include('js/src/jquery-metadata.js'),
		$.include('js/src/jquery.form.js')
	]
);

Smooth Menu widget for jQuery

If You liked Fancy Menu, but not necessarily feel the same to moo.tools (no offence) here You have similar widget for jQuery – Smooth Menu. It works for vertical lists too.

Examples are bare so it’s easier to understand whats needed to implement it to your site. Love to see it in combination with rounder corners (imageless).