PHP

If you are familiar with PHP you will have come across the for loop at some point. When learning JavaScript it is important to remember that it also has the ability to do the equivalent of the PHP forloop.

The following snippet shows the creation of an array of things that can't be referenced by a normal for loop due to the odd numbering of the keys.

var arrThings= new Array();
 
arrThings[3] = 'thing 1';
arrThings[42] = 'thing 2';
arrThings[47] = 'thing 3';
arrThings[32] = 'thing 4';
 
var output = '';
 
for ( var thing in arrThings ) {
 output += arrThings[thing];
}

alert(output);

The variable thing is now the iterator and will iterate through each element of the array. By using this code you no longer have to include code that thinks about the length of the array.

There are three available cryptographic functions in PHP, these are md5(), sha1() and crc32(). All of the functions take a string and output a value that is encrypted and can't be reversed to the original string. In fact the only way to get the original string back is to run a brute force algorithm which tries to guess what the original string was.

To test these functions I will use the following string.

$string = 'wibble';

md5()

This function returns the hash as a 32-character hexadecimal number. The md5() function is used quite a bit and most PHP programmers will have come across it at some point.

Use the following code to create an array of counties in the UK.

The following function will rename all of the image files in a directory to be sequential. The parameters are the path of the directory that the files are in and the name of a function that will be used to sort the array of files through the PHP usort() function.

function sequentialImages($path, $sort=false) {
 $i = 1;
 $files = glob($path."/{*.gif,*.jpg,*.jpeg,*.png}",GLOB_BRACE|GLOB_NOSORT);
 
 if ( $sort !== false ) {
  usort($files, $sort);
 }
 
 $count = count($files);
 foreach ( $files as $file ) {
  $newname = str_pad($i, strlen($count)+1, '0', STR_PAD_LEFT);
  $ext = substr(strrchr($file, '.'), 1);
  $newname = $path.'/'.$newname.'.'.$ext;
  if ( $file != $newname ) {
   rename($file, $newname);  
  }
  $i++;
 }
}

The following function can be used in the second parameter to sort the files by their last modified time.

I have previously talked about using PHP to convert from a date to a time, but what about doing the same in JavaScript?

To get the unix timestamp using JavaScript you need to use the getTime() function of the build in Date object. As this returns the number of milliseconds then we must divide the number by 1000 and round it in order to get the timestamp in seconds.

Math.round(new Date().getTime()/1000);

To convert a date into a timestamp we need to use the UTC() function of the Date object. This function takes 3 required parameters and 4 optional parameters. The 3 required parameters are the year, month and day, in that order. The optional 4 parameters are the hours, minutes, seconds and milliseconds of the time, in that order.

Use the following function if you want to print the text in a particular colour, depending on what the background colour is.

function opposite($color) {
  $white = 0;
  for ($i = 0; $i < 6; $i += 2) {
    $white += base_convert(substr($color,$i,2),16,10) < 127 ? 1 : 0;
  }
  return $white <= 2 ? "000000" : "ffffff";
}

It works by looking at the colour and seeing how much of it is white. If greater than two parts are significantly white then the color returned is black, otherwise white is returned.

Here are some examples to test the function out.

Wordpress has a nice little revisions feature that will allow you to revert to a previous version of a post if you don't like the current edit. However, the drawback of this feature is that it is not always needed and it fills the post table full of stuff you will never need. Fortunately, turning this feature off isn't too much of a pain. All you need to do is add the following line of code to your wp-config file, just below the DB_COLLATE line.

define('WP_POST_REVISIONS', 0);

You can also set the autosave interval here to something greater than the default of 60 seconds. It is possible to do this in the wp-config file since version 2.5.0.

define('AUTOSAVE_INTERVAL', 123);

If you want to get rid off all of the post revisions from your post table then you can use the following SQL query.

This simple code example uses a combination of strrchr to find the last occurrence of a string and substr to return part of the string in order to find the file extension for a given filename. This is ideal if you want to quickly find a file extension.

$ext = substr(strrchr($fileName, '.'), 1);

This code can be used in the following way.

$fileName = '\path\to\file\afile.wibble';
$ext = substr(strrchr($fileName, '.'), 1);
echo $ext;

The output here is 'wibble';

A sortable list is simply a list of items that can be dragged and dropped to alter the order of those elements.

There are two sortable lists available in Wordpress, one from the JQuery framework and one from the Scriptaculous framework. For a sortable list you will need a list, so here is a simple one.

<ul id="sortcontainer">
	<li class="sortable">Item 1</li>
	<li class="sortable">Item 2</li>
	<li class="sortable">Item 3</li>
	<li class="sortable">Item 4</li>
</ul>

JQuery Sortable

The first thing you learn about in PHP is probably how to print something. This is usually done with a call to the echo or print, but there is another way to print things by writing content directly to the output buffer. The following code looks like you are writing to a file, but the text will appear in the browser window because we are writing to the php://output output stream.

$fp = fopen("php://output", 'r+');
fputs($fp, "Hello World");

Or another way...

file_put_contents("php://output", "Hello World");

The php://output stream is an encapsulation between PHP and the browser. The stream doesn't really exist, but PHP knows what to do with it.