Peter Velichkov's Blog

Couple of days ago I had to create a content pager which can dynamically insert page numbers including previous and next buttons.

The reason why I had to use Javascript and not any server side solution is quite interesting - the paging method should not really divide the content into different web pages. This is needed because if the text we want to split contains any XHTML markup and we divide it into separate web pages the markup will be broken (invalid). Just imagine having opening <div> tag in the first page and closing in the second - not cool! Other break point is if we just split some tag in two.

Using my favourite Javascript Framework - Mootools and with couple of XHTML/CSS tricks I could get it working with the following code:

// This Javascript is written by Peter Velichkov (http://www.creonfx.com)
// and is distributed under the following license : http://creativecommons.org/licenses/by-sa/3.0/
// Use and modify all you want just keep this comment. Thanks
 
var pagerPageHeight = $('warper').getSize().y;
var contentArea = $('content');
var pagerCurPage = 1;
var pagerPagesCount = 1;
var pagerPages = $('pager');
 
var pagerInit = function(){
 
	var contentHeight = contentArea.getSize().y ;
	pagerPagesCount = (contentHeight / pagerPageHeight).toInt();
	if (contentHeight % pagerPageHeight != 0 ) pagerPagesCount++;
	if (pagerPagesCount === 1) return;
 
	var prev = new Element('a', {
			'class': 'cust-pager-prev',
			'html': '&lt',
			'id': 'cust-pager-prev',
			'events': {
				'click': function(){
					pagerChangePage(pagerCurPage - 1);
				}
			}
		});
 
	var next = new Element('a', {
			'class': 'cust-pager-next',
			'html': '&gt',
			'id': 'cust-pager-next',
			'events': {
				'click': function(){
					pagerChangePage(pagerCurPage + 1);
				}
			}
	});	
 
	prev.inject(pagerPages,'top');
	$('cust-pager-prev').setStyle('display','none');
 
	for (var i=1; i<=pagerPagesCount; i++){
		var anchor = new Element('a', {
			'class': 'cust-pager-item',
			'id': 'cust-pager-item-'+ i,
			'html': i,
			'events': {
				'click': pagerChangePage.pass(i)
			}
		});
		anchor.inject(pagerPages);
	}
 
	next.inject(pagerPages,'bottom');
};
 
var pagerChangePage = function(page){
	$('cust-pager-item-' + pagerCurPage).set('class', 'cust-pager-item');
	$('cust-pager-item-' + page).set('class', 'cust-pager-item-sel');
 
	pagerCurPage = page;
 
	if (pagerCurPage === 1) {
		$('cust-pager-prev').setStyle('display', 'none');
	}else{
		$('cust-pager-prev').setStyle('display', 'inline');
	}
 
	if (pagerCurPage === pagerPagesCount) {
		$('cust-pager-next').setStyle('display', 'none');
	}else{
		$('cust-pager-next').setStyle('display', 'inline');
	}
 
	contentArea.setStyle('top', (-1) * pagerPageHeight * (page - 1));
};
 
pagerInit();

The example and the picture as usual.

After seeing couple of implementations of replacing the default form checkboxes and radio buttons I was on a search for cross-platform select dropdown which can be fully styled with CSS. Unfortunately there are not so many options and the best I could find is elSelect:

elSelect is a great tool that allows you to visually change look and feel of usual select, keeping its functionality.

However I believe there is plenty of space for improvements.

1. Porting to Mootools v1.2 -

You need to replace setHTML, setText and other deprecated stuff to the new syntax.

2. Instead of creating new input just move the original (otherwise all events connected with the DOM element are lost and it does not work with .NET forms) -

Replace:

this.hiddenInput = new Element('input').setProperties({
			type  : 'hidden',
			name  : this.source.getProperty('name')
		}).injectInside($(this.options.container))

with:

this.hiddenInput = this.source.injectAfter($(this.options.container));

3. Various optimizations + autocomplete functionality and keyboard shortcuts (Tab-ing through the form).

Also I’m checking the browser agent since under iPhone it is better not to replace the select and adding some code graceful degradation:

var addCustomSelect = function(wrapper){
	if(!Browser.Platform.ipod){
		try{
			var mySelect = new elSelect( {container : wrapper});
		}catch(e){}
	}
	if ($(wrapper).getElement('select')) $(wrapper).getElement('select').setStyle('display','inline'); // Select is still here - degrade gracefully
}
if($('cust-sel')) addCustomSelect('cust-sel'); // Call as soon as possible

Other good tip is to have the select (you are replacing) with style visibility:hidden so it does not flicker when loading.

You can download my modified version from here. It has 1 and 2 applied plus some other minor changes. Still it is a good idea to diff the original and my version since I have custom modification that you might not need.

As part of my Mootools lecture at Codecamp I showed a brief speed comparison between the most used Javascript Frameworks running in the major browsers. Now as the Mootools team has extended their performance test tool (slickspeed) it is time to revise my benchmarks and extend them over more browser/platforms.

Test results (Lower is better):

*For example FF (XP-NA) is Firefox 2.0.0.12 with no addons (extensions) enabled running under Windows XP

You can check the actual numbers (in ms) and the full browsers information in the table bellow:

Conclusions:

• Safari under Windows XP is really blazing fast
• Mootools and Prototype JS do not work under Konqueror (KDE’s default browser)
• Dojo performs great. If we take only these test into consideration it safe to say it is the fastest Javascript Framework
• Linux browsers are relatively slower against their Windows versions
• Prototype is insanly slow under Internet Explorer

Disclaimer: This benchmark is somehow subjective because the test results depend on the current OS load and other factors. If you have any corrections or comments on this topic I will gladly review them and will revise the results if needed.

Just refactored the input watermarking script, of course it is still XHTML 1.0 transitional and WCAG priority 1,2 valid.

JavaScript:

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// This Javascript is written by Peter Velichkov (http://www.creonfx.com)
// and is distributed under the following license : http://creativecommons.org/licenses/by-sa/3.0/
// Use and modify all you want just keep this comment. Thanks
 
var values = new Array();
var inputs = new Array();
 
function addWaterMark(el){
	try {
		values.push(el.value);
		el.addEvent('focus',function(){
			if (el.value === values[inputs.indexOf(el)]){el.value = ''};
		});
		el.addEvent('blur',function(){
			if(this.value === ''){el.value = values[inputs.indexOf(el)]};
		});
	} catch(e) {dbug.log('addWaterMark: ', e)}
};
window.addEvent('domready', function(){
	inputs = $$('input.watermark');
	inputs.each(addWaterMark);
});
//-->

Usage: Just put value on you inputs and use class=”watermark”

As usual example

Thanks to Aaron Newton from CNET.com for refactoring my PNG Fix script and increasing its quality and speed.

As usual for dessert explanations + demo and source code

Update: A far more better approach is to dynamically replace <select>’s in the HTML. Here is my post on the topic - Customizable Form Select / Dropdown Replacement with Mootools

Got tired of not able to style (colors, padding, background image, etc) dropdowns under various browsers (Internet Explorer and Safari are proven worst). Using my very favorite javascript framework mootools I created some simple dropdown simulating the select and option html tags usage.

Picture == thousand words

and example of custom styled dropdown

As always when I need to use some transparent images cursing Internet Explorer 6 is inevitable so i wrote a quick javascript fix. Again mootools was the preferred framework because the ease of use.

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// This Javascript is written by Peter Velichkov (www.creonfx.com)
// and is distributed under the following license : http://creativecommons.org/licenses/by-sa/3.0/
// Use and modify all you want just keep this comment. Thanksfunction fixPNG(){
 
 $$('*').each(function(el){
 
 	var imgURL = el.getStyle('background-image');
 
 	var imgURLLength = imgURL.length;
 
 	if ( imgURL != 'none' && imgURL.substring(imgURLLength  - 5, imgURLLength  - 2) == 'png'){
 
 		el.setStyles({
 
 			background: '',
 
 			filter: "progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled='true', sizingMethod='crop', src='" + imgURL.substring(5,imgURLLength  - 2) + "')"
 
 		});
 
 	};
 
if(el.getTag() == 'img' && el.getProperty('src').substring(el.getProperty('src').length  - 3) == 'png'){
 
 		var imgReplacer = new Element('input', {
 
 			'styles': {
 
 				'filter': "progid:DXImageTransform.Microsoft.AlphaImageLoader(enabled='true', sizingMethod='crop', src='" + el.getProperty('src') + "')",
 
 				'position': 'relative',
 
 				'background': 'transparent'
 
 			},
 
 			'title': el.getProperty('alt')
 
 		});
 
imgReplacer.setStyles(el.getStyles('padding','margin','border','height','width'));
 
 		imgReplacer.setProperties(el.getProperties('id','class'));
 
 		imgReplacer.disabled = true;
 
 		el.replaceWith(imgReplacer);
 
 	};
 
 });
 
}
 
if(window.ie6){
 
 window.addEvent('domready', fixPNG);
 
}

Fix description: First I’m looking for all tags that have background-image style and replace it with Microsoft AlphaImageLoader filter, then I search for all <img> tags and replace them with <input> (img src used for style background image again using the MS filter). I used input since it is inline element but still has height and width - like the img tag.

PS. If you use any links in area with PNG used for bg put the links in div with style=”position:relative” else they will not be clickable due to the MS filters

and as always example: IE6 PNG Transparency Fix with JavaScript