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To have a well-formed XHTML document, you must put all references to Javascript and CSS files within the <head> portion. Since Joomla! generates all of the HTML that makes up a page before output, it is possible to add these references to the <head> tag from your extension. The simplest way to do this is to make use of the functionality built in to Joomla!:
// Add a reference to a javascript file
// The default path is 'media/system/js/'
JHTML::script($filename, $path, $mootools);
// Add a reference to a CSS file
// The default path is 'media/system/css/'
JHTML::stylesheet($filename, $path);
Using these functions, Joomla! will take care of any additional requirements. For example, if your javascript requires Mootools, setting $mootools = true will automatically ensure that Mootools is loaded, if it has not already been done.
However, the above functions will not be flexible enough for every scenario, and so it is possible to tap into the underlying functionality instead. (Of course, this means that you will also need to manually code some of the steps that would be done automatically using the functions above!)
Firstly, you will need to get a reference to the current document object:
$document =& JFactory::getDocument();
To add a javascript file, use this code:
$document->addScript($url);
Note that this will not automatically include Mootools. If your script requires Mootools, you should also include the line:
JHTML::_("behavior.mootools");
For a stylesheet, use this code:
$document->addStyleSheet($url);
However, your javascript or CSS might not be located in a separate file - you might want to generate them using PHP. In this case you can write the script/stylesheet directly into the head of your document:
// Add javascript
$document->addScriptDeclaration($javascript, $type);
// Add styles
$document->addStyleDeclaration($styles, $type);
For example, the following code is used to define a custom tool tip that takes advantage of mootools.
function getToolTipJS($toolTipVarName, $toolTipClassName){
$javascript = 'window.addEvent(\"domready\", function(){' ."\n";
$javascript .= "\t" .'var $toolTipVarName = new Tips($$("' . $toolTipVarName .'"), {' ."\n";
$javascript .= "\t\t" .'className: "' .$toolTipClassName .'",' ."\n";
$javascript .= "\t\t" .'initialize: function(){' ."\n";
$javascript .= "\t\t\t" .'this.fx = new Fx.Style(this.toolTip, "opacity", {duration: 500, wait: false}).set(0);' ."\n";
$javascript .= "\t\t" .'},' ."\n";
$javascript .= "\t\t" .'onShow: function(toolTip){' ."\n";
$javascript .= "\t\t\t" .'this.fx.start(1);' ."\n";
$javascript .= "\t\t" .'},' ."\n";
$javascript .= "\t\t" .'onHide: function(toolTip) {' ."\n";
$javascript .= "\t\t\t" .'this.fx.start(0);' ."\n";
$javascript .= "\t\t" .'}' ."\n";
$javascript .= "\t" .'});' ."\n";
$javascript .= '});' ."\n\n";
return $javascript;
}
$document =& JFactory::getDocument();
$document->addStyleSheet("/joomla/components/com_mycustomcomponent/css/mytooltip.css",'text/css',"screen");
$document->addScriptDeclaration(getToolTipJS("mytool","MyToolTip"));
(Note that, in order for this javascript to be functionally useful, it would be necessary to include the appropriate class name in the HTML, as well as providing the mytooltip.css file. Both are outside the scope of this article.)
There will be some occasions where even these functions are not flexible enough, as they are limited to writing the contents of <script /> or <style /> tags, and cannot add anything outside those tags. One example would be the inclusion of a stylesheet link within conditional comments, so that it is picked up only by Internet Explorer 6 and earlier. To do this, we can use $document->addCustomTag:
$stylelink = '<!--[if lte IE 6]>' ."\n";
$stylelink .= '<link rel="stylesheet" href="/../css/IEonly.css" />' ."\n";
$stylelink .= '<![endif]-->' ."\n";
$document =& JFactory::getDocument();
$document->addCustomTag($stylelink);
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