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Dealing with CSS unit conversions in jQuery (px to em to percentages)

I spent some time working on a plugin to convert px to em and percentages for the upcoming Wordspot site.

The problem lies in the fact that measurements are based on the element they are attached to. Thus, to convert any CSS property (i.e. “5em” or “20%”) to pixels, one must determine what the relative height of a single line of text is in pixels.

This tool creates an invisible child element, measures a single line of text, and uses that for measurements.

Thus, to convert 90% (or any measurement, for that matter) to pixels, you could do the following:

   var borderRadiusPixels = $.UnitConverter.px( $('#mydiv').css('border-top-left-radius') );

Here’s the source.

For more advanced operations, you can do things like this:

   // create a new unit conversion
   var measurement = new $.UnitConverter( $('#mydiv') );
   // load a value to be examined
   measurement.load( $('#mydiv').css('border-left-width') );
   // add 10% to the height
   measurement.add( '10%' );
   // convert the measurement to various output types
   var pxs = measurement.px();
   var ems = measurement.convert( 'em' );
   var pct = measurement.convert( '%' );
   // determine what the measurement would be in another element (i.e. with a different line height)
   var clonePxs = measurement.clone( $('#nudderElement') ).px();

Hopefully this will give you a good head start on conquering similar issues, without having to invent any wheels!

Regular expressions tester for your regex fiddling

I was teaching a good friend a bit about regular expressions and wrote up a regular expression tester. It was a blast to write and simple to implement. It’s all in one HTML page so you can download it and fiddle away. Hope it helps someone else as well:

Advanced Bash Scripting Guide

This guide really is a complete resource for understanding bash syntax; very easy to get around and understand.

remote debugging PHP for a single virtualhost with PhpStorm and xdebug

I struggled for several days to set up remote debugging. I wanted to be able to remotely debug a single virtualhost on my CentOS server using my local IDE (PhpStorm) and xdebug.

Since this took me quite a while to figure out, I thought I’d include the steps here for others.

Installing Xdebug

Over SSH, I ran the following:

$ pecl install xdebug

Configuring Xdebug in php.ini

; Module Settings ;

Note the use of zend_extension; as of PHP 5.3, this is the only one that works (extension=…) will appear to function, but never connect!

Also, I used xdebug.remote_connect_back=1 – this allows connections from anywhere. But since I’ve configured my server to load a separate php.ini for each site (sorry, this is outside the scope of this discussion), and the entire site is under development and protected by .htaccess, I didn’t have to worry about other people debugging remotely.

An alternative to using remote_connect_back is to specify the remote_host to your local ip address:

xdebug.remote_host= ;your ip address

 Alternative: Loading via .htaccess instead of php.ini

Alternately, I could have dropped a .htaccess file into my root directory for the virtualhost, if the php.ini for each site were too much trouble:

php_value  zend_extension=/usr/lib/php/modules/
php_flag   xdebug.remote_enable on
php_value  xdebug.remote_port 9000
php_value  xdebug.idekey PHPSTORM-XDEBUG
php_flag   xdebug.remote_connect_back on

Configuring PhpStorm

I followed these instructions to the letter. Make sure you set up the “PHP Remote Debug” and not the “PHP Server” option if you’re using my list here as a guide (both work, I just chose the remote)

Remember to get those IDEKEY values to match up in the editor and on the server!

Configure Firewalls

On CentOS, I use apf, so I configured my firewall by adding port 9000 into the following settings: IG_TCP_PORTS, EG_TCP_PORTS

Then I restarted apf:

$ /etc/init.d/apf restart

At home, I opened a connection in my firewall by adding a redirect for port 9000 to my personal PC.

Starting it Up

Remember to reload Apache’s config!

$ /etc/init.d/httpd reload

Make sure PhpStorm is set to break on first line, or you won’t know if it worked! (you need the debugger to get involved):


Start the PhpStorm Remote Debug:


Make sure to click the “listen for connections” icon!

A quick note on semantics here: It is not technically necessary to have the debug server running and “listen for connections” clicked. Listen for connections will, in fact, start the debugger when an incoming connection is received. However, for initial testing, having the debugger actually ON was very helpful in being sure PhpStorm wasn’t failing to start incoming connections.


Connect to your IP address from the web server to make sure it can talk to your IDE:

$ telnet 9000


Add XDEBUG_SESSION_START=PHPSTORM-XDEBUG in the URL of the site to initiate a connection:


Witness debugging in all its glory!


Browser Plugins

There are browser plugins for Chrome and Firefox that make remote connections a breeze; you no longer have to type the parms into the URL. I’ve used both of these with success and highly recommend this simplification.

Flash cards for jQuery certification

I’ve been studying up for a jQuery certification.  I created a set of almost a thousand flash cards to prepare. I’ll be adding more for the jQuery UI in the near future.

This is a great site as once registered, you can check any number of the flash cards sets, then say “study 50″ or “study 100″ and it will give you a random cross section of the sets to study for the day. It tracks correct/incorrect and provides charting, as well as some other nice tools (keyboard navigation–yay!)

making Freeow work with jQuery 1.2.6


I was able to make this lib work with jQuery 1.2.6 by making only this one-liner change:

    this.element.hover(this.options.onHover, this.options.onHover);

Project Management and Time Tracking

The world of Time Tracking and Project Management is a vast one. For small businesses like ours, there are seemingly endless time tracking solutions and a good number of project management answers.  I spent nearly two weeks evaluating options in my spare time, so hopefully this data will help save you some time.

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Get elements by CSS class name in javascript

Dustin Diaz wrote a nice, efficient version of getElementByClassName(), which searches HTML elements and retrieves all the items with a given CSS class specified.

Of course, if you use a lib like extjs, jQuery, et al, then you have no need of this. But if you’re trying to hack out a greasemonkey script or insert some minimalist code, here it is.

And here it is, for my own archives:

function getElementsByClass(searchClass,node,tag) {
	var classElements = new Array();
	if ( node == null )
		node = document;
	if ( tag == null )
		tag = '*';
	var els = node.getElementsByTagName(tag);
	var elsLen = els.length;
	var pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)");
	for (i = 0, j = 0; i < elsLen; i++) {
		if ( pattern.test(els[i].className) ) {
			classElements[j] = els[i];
	return classElements;

Here’s another alternative I found on Glazblog, using xpath to search the document:

document.getElementByClassName = function(needle) {
  var xpathResult = document.evaluate('//*[@class = needle]', document, null, 0, null);
  var outArray = new Array();
  while ((outArray[outArray.length] = xpathResult.iterateNext())) {
  return outArray;

I don’t really know which is more efficient, though I suspect the xpath search could be taxing in very large documents. I’m positive, based on IE’s fake implementation of key/value pairs in the DOM, that they both suck in IE, even if you specify a specific tag type to search. Obviously, providing a node makes the regular expression search faster, by virtue of having less content to parse.

Sending Mail From Bash Scripts with an Attachment

Here is a great little tut on getting started in Bash. I’d recommend it to anyone trying to hack their way into a shell script.

Here is a quick script for sending an email:

# Subject of email
SUBJECT="Test email with attachment from a bash script"
# Where to send it
# Where the attachment is
# For fun, let's put something into the attachment
echo "This goes into the file."  >  $ATTACHMENT_FILE
echo "This appends to the file." >> $ATTACHMENT_FILE
# send the message

Manually remove a service from windows

Today I needed to manually remove a service from windows. I found this command line approach, which worked great for me.  Be sure to use the service name and not the display name:

sc delete ServiceName

You can find the service name by going to Control Panel -> Administrative Tools -> Services, right click the service and choose properties, the service name is shown there.

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