May 31 2009

Javascript DOM List Swap Nodes Example

I couldn’t find an easy to follow example to do this anywhere on the web so I did my own up. Basically I wanted a list where each item has an up and a down button that will dynamically reorder the list. I tried swapping the nodes themselves but it didn’t work so it seems that I have to use the removeChild and insertBefore methods to actually see the results on the page.
Here is the Javascript DOM Example

<ul id='list' name='list'>

<script type='text/javascript'>

//swap the current li node with the one above it
function up(button_node)
  var current_node = button_node.parentNode;
  var list_children = document.getElementById('list').childNodes;
  var list_node = document.getElementById('list');
  var temp_node;
  var previous_node;
  for(var i=0;i<list_children.length;i++)
    if( == list_children[i].id && previous_node)
      temp_node = list_children[i].cloneNode(true);

//swap the chosen li node with the one below it
function down(button_node)
  var current_node = button_node.parentNode;
  var list_children = document.getElementById('list').childNodes;
  var list_node = document.getElementById('list');
  var temp_node;
  var previous_node = "";
  for(var i=0;i<list_children.length;i++)
    if( == list_children[i].id)
    else if(previous_node && list_children[i].tagName=='LI')
      temp_node = list_children[i].cloneNode(true);
      previous_node = "";

//create the li elements
function create_list()
  for(var i=0;i<6;i++)
    add_li('list', "Item "+i," Item "+(i+1)+" \
    <input type='button' id='up_button1' value='Up' onclick='up(this);'>\
    <input type='button' id='down_button1' value='Down' onclick='down(this);'>");

//add a li element
function add_li(list, id, text) {
  var list = document.getElementById(list);
  var li = document.createElement("li");
  li.innerHTML = text;;


So it is a little longer than I expected but it works and it’s pretty easy to understand.


May 30 2009

Django Quick Install With WSGI

Django is a high level python web framework that I’ve been hearing a lot about lately. I decided to try it out this weekend.
It took a little reading to get up and running so I documented the steps I took so others can get up and running a little more quickly.

sudo apt-get install django
django-admin –version

Create the appropriate directories and start the django project.

For no real reason I decided to put my new projects in /var/django.
sudo mkdir /var/django
sudo chmod 755 /var/django
cd /var/django
django-admin startproject mysite
cd mysite
mkdir apache

It seems that mod-wsgi is the best way to serve up python web apps due to mod_python being a little outdated. Note that django does come with a built in webserver that is really easy to get going. So if you’re just planning on evaluating the framework and not actually do any production aplications then that would be the way to go. mod_wsgi is an Apache module which can be used to host Python applications.

Install the module:
sudo apt-get install libapache2-mod-wsgi

Now for the configuration. It took me a few tries to get this right.
For now I just put my django site on port 8080 so I can play around without it being public to anyone else.

In the /var/django/mysite/apache directory I created a file called django.wsgi and put this in it:

import os, sys
apache_configuration= os.path.dirname(__file__)
project = os.path.dirname(apache_configuration)
os.environ[‘DJANGO_SETTINGS_MODULE’] = ‘mysite.settings’
import django.core.handlers.wsgi
application = django.core.handlers.wsgi.WSGIHandler()

Make sure that the sys.path.append line contains the directory above the project directory. This one took me awhile to figure out.
I was getting this error until I got it right.

[Sat May 30 15:33:24 2009] [error] [client]     raise ImportError, “Could not import settings ‘%s’ (Is it on sys.path? Does it have syntax errors?): %s” % (self.SETTINGS_MODULE, e)
[Sat May 30 15:33:24 2009] [error] [client] ImportError: Could not import settings ‘mysite.settings’ (Is it on sys.path? Does it have syntax errors?): No module named mysite.settings

Next I added a new virtual host in my sites-enabled folder like this:

<VirtualHost *:808http://localhost:8080/0>
<Directory /var/django/mysite/apache>
Allow from all

WSGIDaemonProcess www-data
WSGIProcessGroup www-data
WSGIScriptAlias / /var/django/mysite/apache/django.wsgi

After restarting apache :
sudo /etc/init.d/apache2 restart

I got an “It Worked” page when I point my browser to http://localhost:8080/

Of course this doesn’t allow you to use a database in your applications yet but it’s a start.


May 28 2009

Simple and Slick Dojo Fisheye Effect

Firstly check out the effect example. Hover over the list in the middle to see the effect. This is called the fisheye effect in dojo and it’s one of my favorites because it’s the easiest to implement. It’s ridiculously easy to implement. I’m going to assume that you know what a basic html page looks like, so in a quick three parts here’s the code:

First the Javascript:

<script type=”text/javascript” src=”includes/dojo/dojo/dojo.js” djConfig=”parseOnLoad: true”></script>

<script type=”text/javascript”>

//make the list items into fisheye items
dojo.query(“”, dojo.byId(“fishyList”)).forEach(function(n){
new dojox.widget.FisheyeLite({ },n);

Next the CSS:

<style type=”text/css”>
@import “includes/dojo/dojo/resources/dojo.css”;
@import “css/dojo_lists.css”;
#fishyList ul {
.fisheyeTarget {

None of the CSS really matters as far as functionality goes. It does go a long way into making it look a lot slicker.

Now the HTML:

<ul id=”fishyList”>
<li class=”fish”><span class=”fisheyeTarget”>Cody Taylor’s<br><br></span></li>
<li class=”fish”><span class=”fisheyeTarget”>Dojo Javascript <br><br></span></li>
<li class=”fish”><span class=”fisheyeTarget”>Slick FishEye Effect<br><br></span></li>

Of course you’ll have to download and put the dojo framework on your webserver and alter the include statements but other than that it’s that simple. You may want to look at the dojo documentation for the dojo.query and forEach functions.


May 27 2009

New PHP 5.3 Release June

Q2 is basically April, May, and June and the 5.3 timeline says Q2 stable release. I’ve been reading mostly good things about the experimental release and considering all the new features being added every php developer should be stoked. I’m not just talking about the new closures/lambda functions which are gonna make my life a lot more fun. Here’s a list of all the fun stuff that I’ll be playing with next month:

  • Namespace support. It’s about time.
  • Late static binding. Somewhere between static and dynamic binding.
  • Jump label (limited goto)
  • Native closures. Simple javascript-like lambda functions. None of that create_function stuff anymore.
  • PHP archives (phar). Not sure why?
  • Garbage collection for circular references.
  • Ternary shortcut. Still haven’t seen an example of what this is?
  • Internationalization extension.

I’ve always been told that goto’s are bad programming practice but sometimes they can be very, very useful. Hopefully they get all the bugs out in the experimental versions and I can start using it at work  shortly after release.


May 26 2009

Anonymous (Lambda) Functions in PHP.

I’ve recently been playing with anonymous (lambda) functions in javascript and I was thinking that it would be great if I could do the same thing in php, which is what I spend most of my time with. Turns out that you can. It’s not as clean and pretty as with javascript but it’s still a lambda function and functional programmers are better…aren’t they?

First the spec :
string create_function ( string $args , string $code )

So here’s a little example of something completely useless that can be done using anonymous functions in PHP :

$first_arg = 100;
$some_function = create_function(‘$first_arg’,’return $first_arg/5;’);

function process($arg,$func)
    return $arg;

echo process($first_arg,$some_function);

So we get 25 echoed to the screen. A bunch of better examples can be found at the php website. If you’re willing to read…

Nothing really special but It’s still cool that can pass functions into another PHP function just like a regular variable.


May 24 2009

Recursive, Anonymous, and Simple functions in Javascript

Functions are objects. This makes recursion short and sweet in javascript using anonymous functions.
In your html, php, or asp file try this out.

<input type=’button’ id=’myButton’ value=”5″>

<script type=’text/javascript’>
var myButton = document.getElementById(“myButton”);
var i=myButton.value;

myButton.onclick = function() {
myButton.value = i;
return i;
return arguments.callee(–i);


I attached the anonymous function onto the onclick event for the button that was created right above the javascript. When that button is clicked the anonymous function will call itself and decrement ‘i’ until it is zero. When ‘i’ becomes zero the value of the button is set to 0 and the function returns. Nice and simple.

The only possible confusing thing here is the arguments.callee line. Remember I said that functions are objects? The arguments.callee actually calls itself. We need this because we don’t have a handle for the anonymous function. The arguments object is a local variable that all functions have. It can be used like an array to access the values passed to the function. It also holds ‘callee’, ‘caller’, and ‘length’. Since the callee is the function itself then caller is obviously the function that called it and length is the number of arguments passed to the function.


May 24 2009

Anonymous Function Examples in Javascript

Learning javascript by copying and pasting useful snippets off the web, the only aspects of Javascript that I’ve ever looked closely at were to change css properties, validate forms, or get some values with ajax. Because of this, there is still  a large portion of the language that I’m still learning. I’ve never used anonymous functions in any language, but they’ve always looked like an interesting concept, so I decided to give it a shot. This is what I learned with a few short examples.

This little javascript feature can be hugely useful for passing functions as variables or declaring quick functions inline for the programmer who is to lazy to switch files or scroll to wherever that annoying javascript declaration is.

To pass a function as a variable either with a reference or inline:

<script type=’text/javascript’>

//garbage example data
var array = [ 3, 14, 15, 9, 26 ]
var array2 = [ 3, 14, 15, 9, 26 ]

//This function takes an array and a function as parameters.
//It then executes the passed function on every element of the array.
function execute_on_array( array_of_stuff, anonymous_function )
    for (var i=0; i<array_of_stuff.length; i++)
        alert(“before ” + array_of_stuff[i]);
        array_of_stuff[i] = anonymous_function(array_of_stuff[i]);
        alert(“after” + array_of_stuff[i]);

//Here’s the anonymous function that is now referred to as nullify_function
var nullify_function = function (x) { if(x) return 0; else return x; }

//Passing an anonymous function in as a variable
execute_on_array( array_of_numbers, nullify_function);

//Here is the call to the previous function with an anonymous function defined inline
function execute_on_array( array2, function (x) { x=0; return x; } );


I could see how this would make recursion in javascript really easy.


May 20 2009

unzip and unrar bash script

Do you ever download those files that are comprised of multiple zip files that always seem to extract individual rar files to their own folders. This would normally require the user to cut and paste all these rar files back into the original folder and then unrar them. This is very tedious, especially when there is lots of these files and folders. I’ve written this little shell script to automate this task for myself and figured that I would share. This script is extremely simple but it has worked great for every double archive that I have tried it on. As always any improvements and comments are welcome.

Call this script from the command line when your current working directory is the folder with all the zip files in it. To get your current working directory use the command ‘pwd’.

unzip -o \*.zip
for f in *.rar;do unrar -o- e “$f”;done
rm *.rar
rm *.zip

You may be asking why I was forced to escape the ‘*’ in the first line. If I didn’t do this then I got a lot of “caution: filename not matched:” errors on the unzip line. Not sure why and if anyone can shed some light on that it would be great. As for the option to the commands, read the man pages. And the for loop is pretty self explanatory.

Enjoy those giant image sets.


May 15 2009

Dojo Examples and Demos

The best resource for browsing all the features of dojo javascript is here. It not only displays all the features of dojo javascript but it also allows you to get any code for any feature you want. Check out here what you can do with it.


May 14 2009

Iphone iwebkit Example

Create Custom Iphone or Ipod Touch Web Applications Using iWebKit

For the impatient people like myself, heres what it looks like. You want to point your iphone browser to this location and hit the ‘+’ button at the bottom and select add to the homescreen. This will get rid of the navigation bar on in safari and make the iwebkit example look like a native iphone app.

Here are the steps to take in order to get this working.
Get the frame work: iWebKit framework (I used 4.5.3 for this guide)
Extract the iwebkit and take a look at the manual. Iwebkit comes with a few examples of how to use the key framework elements.We’re going to make a very rudimentary application for the purpose of iphone iwebkit example. Ajax integration with iwebkit will come later.

First you will need to create a directory on your web server and extract the iwebkit files into it.
The webkit contains a few examples but most of them didn’t show up properly for me when I used the Iphone.
Most webapps are built with just really basic html. The custom elements that iwebkit provides are called by normal divs with certain ids.

First start with an extremely basic html skeleton page :

<meta content=”yes” name=”apple-mobile-web-app-capable” />
<meta content=”text/html; charset=iso-8859-1″ http-equiv=”Content-Type” />
<meta content=”minimum-scale=1.0, width=device-width, maximum-scale=0.6667, user-scalable=no” name=”viewport” />
<title>iphone iwebkit example</title>


Hopefully no explanations are needed there. Notice the meta tags? So now we need to start adding the iphone javascript and css.
To get started with iwebkit for the iphone or iphone touch you only need to include two files into this basic html page but you will need to take all four folders from the Framework folder and put them into the directory where you want to host your web app.
Add these two lines to the head portion of the skeleton html file outlined above.

<link href=”css/style.css” rel=”stylesheet” type=”text/css” />
<script src=”javascript/functions.js” type=”text/javascript”></script>

Now to start putting the application together using iwebkits basic elements.

Top Bar
This section will outline the options for the navigation bar at the top of the page on the iphone or ipod touch.
Using iwebkit for the top bar we will normally put navagation buttons and a title like this.

<div id=’topbar’>
<div id=”leftnav”>
<a href=”index.html”><img alt=”home” src=”images/home.png”/></a>
<div id=’title’>
iphone iwebkit example
<div id=”rightnav”>
<a href=”index.html”>Next</a>

There are four div elements there that make up this top bar. The first is the bar itself and it encompasses the other three elements.
The second is the leftnav div. This specifies that the elements within this div are to appear at the left side of the bar (Big surprise).
The third is the title. The fourth is the rightnav which will appear on the right side. You’re probably going to want to put links and pictures in the leftnav and rightnav divs.
Instead of the rightnav div it is possible to put a rectangle button instead of the arrow button just by changing rightnav to rightbutton in the id.

This section is for basically anything you want to put in your iwebkit page. I’m going to demonstrate a simple iphone-looking list here:

<div id=”content”>
<span class=”graytitle”>Iphone iwebkit example</span>
<ul class=”pageitem”>
<li class=”textbox”>
<p>Some Text for the iwebkit example</p>
<p>More text for the Iphone</p>
<li class=”textbox”>
<span class=”header”>Iphone iwebkit</span>
<p>Iphone Iphone</p><p>WebKit WebKit</p>
<li class=”menu”>
<a href=”index.php”>
<img alt=”Description” src=”thumbs/basics.png” />
<span class=”name”>Iphone iwebkit Example</span>
<span class=”comment”>Comment about iwebkit</span>
<span class=”arrow”></span>
<li class=”store”>
<a class=”noeffect” href=”index.php”>
<span class=”image” style=”background-image: url(‘image.jpg’)”></span>
<span class=”name”>Iphone Song</span>
<span class=”comment”>iWebKit Comment</span>
<img alt=”rating” class=”stars” src=”images/4stars.png” />
<span class=”starcomment”>13 Reviews</span>
<span class=”arrow”></span>


There are a lot of options when using iwebkit. Most are pretty self explanatory, like the <ul> class and the <span> and <li> classes, but who wants to remember all that.
So go check the source of some feature or look that you want on your iwebkit page at <a href=’’>this demo</a>.

The first issue I had when looking at my iwebkit example on the iphone was that the example iwebkit application wasn’t fullscreen in safari.
The only way that I’ve found so far to make this web application look like a native iphone application is to go to the page in safari and then hit the ‘+’ button at the bottom and select add to the homescreen.
This will get rid of the navigation bar on the iphone and make the iwebkit example look like a native iphone app.

This example and the full source for this iwebkit iphone example  can be looked at here.