Behaviour Javascript framework Contrib

This contrib packages the third-party Behaviour Javascript event library, available from http://bennolan.com/behaviour/.

Behaviour uses CSS selectors to subscribe to javascript event handlers. This allows to create clean code, separated from HTML (and well suited to create javascript based interaction that degrades nicely when javascript is not available).

Introduction

From the website:

After all the work of WASP and others to promote clean markup, valid pages and graceful degradation via css - it sucks that we're going back to tag soup days by throwing javascript tags into our html.

The better way to do javascript is to do it unobtrusively. PPK and Simon Willison have been recommending this approach for ages. And it's definitely the way to go. The only problem is that it's a bit of a pain in the ass.

That's why I came up with Behaviour - my solution to unobtrusive javascript behaviours.

How does it work?

Behaviour lets you use CSS selectors to specify elements to add javascript events to. This means that instead of writing:

<li>
   <a onclick="this.parentNode.removeChild(this)" href="#">
      Click me to delete me
   </a>
</li>

You can use:

<ul id="example">
   <li>
      <a href="/someurl">Click me to delete me</a>
   </li>
</ul>

And then use css selectors to select that element and add javascript functions to it.

var myrules = {
   '#example li' : function(el){
      el.onclick = function(){
         this.parentNode.removeChild(this);

      }
   }
};

Behaviour.register(myrules);

Usage

Include the javascript file:

<script type="text/javascript" src="%PUBURL%/%SYSTEMWEB%/BehaviourContrib/behaviour.compressed.js"></script>

In your code you create a "rules" object, with sub-objects for each html element class name or id:

var myrules = {
   '.classname' : function(element) {
      // element event
      element.onclick = function() {
         // code here
      }
   },
   
   '#id' : function(element) {
      // element event
      element.onclick = function() {
         // code here
      }
   }
};

Or use nested identifiers:

var myrules = {
   '.menu li a' : function(element) {
      element.onclick = function() {
         // code here
      }
   }
};

Apply the rules with:

Behaviour.register(myrules);

Example

If we have a 'normal' link to TWiki Web hometopic: TWiki Web Home, we can use javascript to make it open a popup window. When javascript is not available the link behaviour defaults to opening the page in the current window.

<span class="link%SYSTEMWEB%%HOMETOPIC%">[[%SYSTEMWEB%.%HOMETOPIC%][TWiki Web Home]]</span>

<script type="text/javascript">
// <![CDATA[
var myrules = {
   '.link%SYSTEMWEB%%HOMETOPIC% a' : function(el){
      el.onclick = function() {
         // open in a popup with no other attributes than template 'viewplain'
         twiki.Window.openPopup(this.href,{template:"viewplain"});
         return false;
      }
   }
};

Behaviour.register(myrules);
// ]]>
</script>

The class name link%SYSTEMWEB%%HOMETOPIC% will get expanded to linkTWikiWebHome

Creates:

TWiki Web Home

Leaking danger

Behaviour code leaks memory on Windows Explorer prior to version 7. To prevent leaking, set the element variable to null:

var myrules = {
   'table.test td' : function(element) {
      element.onmouseover = function() {
         this.style.backgroundColor = "yellow";
      },
      element.onmouseout = function() {
         this.style.backgroundColor = "";
      }
      element = null; // by setting this IE will not leak  
   }
};   
Behaviour.register(myrules);

Code update notes

Version 1.1 with faster DOM queries

Windows Explorer suffers from slow DOM querying. That means that IE will choke on long pages whenever Behaviour code is used.

Dean Edwards has written up code to let IE run faster DOM queries, with a speed-up hack to Behaviour. This code - updated to make it run cross platform - is now integrated into the distributed javascript. Firefox and Safari won't get any faster than they are, but on IE the speed difference is significant.

Version 1.2 with faster DOM queries (again)

Another speed update to call Behaviour's apply earlier than on page onload (which happens when all images have been downloaded). Support for Explorer, Firefox, Safari and Opera 9.0b2.

Development

• Google Groups: Behaviour Javascript Library
• Nabble - Behaviour Javascript Library forum & mailing list archive
• Behaviour2 - update in the making, since 2006

License

Behaviour is freely distributable under the terms of an BSD license. For details see the Behaviour website.

Links

• Behaviour website
• Behaviour Google Group

Distribution files

• compressed javascript file (3.6K) - processed by ShrinkSafe
• behaviour.js (9.7K) - original javascript source

Contrib Settings

• Set SHORTDESCRIPTION = Behaviour Javascript event library to create javascript based interactions that degrade well when javascript is not available

Contrib Info

Author:	TWiki:Main.ArthurClemens
Copyright:	Code: behaviour.js version 1.1 - Copyright (c) Ben Nolan and Simon Willison. TWiki distribution and updates/additions: TWiki:Main.ArthurClemens.
License:	BSD
Dependencies:	%$DEPENDENCIES%
Contrib Version:	1.2.3
Change History:
02 Jul 2007	1.2 Integrated other faster code by Dean Edwards: faster onload (again).
08 Mar 2007	1.1 Integrated code by Dean Edwards (see Code update version 1.1 with faster DOM queries).
04 Jun 2006	1.0 First Version. Included Behaviour version: 1.1.
Home:	http://TWiki.org/cgi-bin/view/Plugins/BehaviourContrib
Feedback:	http://TWiki.org/cgi-bin/view/Plugins/BehaviourContribDev
Appraisal:	http://TWiki.org/cgi-bin/view/Plugins/BehaviourContribAppraisal

Related Topics: TWikiPreferences