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A good usability feature of web forms is to fill the contents of one drop down menu, depending on what has been selected in a previous menu. This can be done quite easily with JavaScript.

Take the following form, in this instance I have used some server variables used in mod_rewrite, but the idea is valid.

Wordpress has a neat little feature that allows you to write a post and then schedule it to display at some point in the future. This seems good, but it invariably doesn't work on some server platforms and rather than publishing a post Wordpress just counts the amount of time passed since it was supposed to go live. The basic solution to this is to go into the post and click on publish, which can be a pain if you are taking a couple of days off from blogging and want to leave it running.

The problem lies with the functions that convert a scheduled post into a live post which are kept in the file wp-cron.php in the root Wordpress directory. For some reason the Wordpress developers decided to call the scheduling functions using the fsockopen() function available in PHP. This essentially opens a browser session to the wp-cron.php file, just as you would if you browsed to the location using your web browser.

If you have lots of check boxes in a row a handy little usability trick is to allow a user to click on a button and check all of the checkboxes at once. The following function will either check or uncheck all of the check boxes in your form.

function check_uncheck(truefalse){
 var boxes = document.forms[0].chkboxarray.length;
 var form = document.getElementById('checkForm');
 for(var i=0;i < boxes;i++){
  if (truefalse) {
   form.chkboxarray[i].checked=true;
  } else {
   form.chkboxarray[i].checked=false;
  }
 }
}

All you need to do is to add two buttons to your form that will allow users to either check or uncheck the boxes on the form. The function takes a single parameter, which is what to set the value of the check boxes to, so one button is needed to set them to checked and one to unchecked.

A normal procedure with banner adverts is to rotate them randomly, but also to display some more than others. Lets say that you had 3 banner adds and that you wanted to display them at different rates. To do this you can use the rand() function to generate a random number that can then be used to see what banner advert will be displayed.

First we generate the random number, in our case it is between 1 and 100.

$number = rand(1, 100);

You can then use this number to figure out what banner ad to display. Because the random number is between 1 and 100 it is basically a percentage. So you can create a simple if statement that will determine what banner should be displayed.

You will sometimes want to make sure that your code is a better hidden from the end user. For example, you might want to make sure that your database password files are completely hidden from prying eyes so that even if your web server is hacked your database server isn't also compromised.

Take the following code, which prints out "Hello world".

echo "Hello world";

You can encode this into meaningless text by using the base64_encode() function.

$code = base64_encode('echo "Hello world";');

This turns the $code variable into the following.

ZWNobyAiSGVsbG8gd29ybGQiOw==

Which can be run again by using the bade64_decode() function in conjunction with the eval() function.

Firebug is by far the best JavaScript debugging plug-in available for Firefox. I have been stuck on a few problems in the past and Firebug has usually provided me with a reason as to why things are going wrong. In fact when developing for other browsers (like Internet Explorer) I can feel a little blind as there are no debugging tools with the power and features of Firebug. It can allow you to stop JavaScript execution at any time using breakpoints.

Firebug is important if you are creating AJAX applications as it will tell you about every client/server communication, what headers where sent and what the response was.

Using timestamps is quite a common practice, but converting them into "real life" times can be a little hard. So here are some common time intervals that you might need.

Hypertext access, or .htaccess files, allow you to change the Apache configuration on a by directory basis. However, you should always use the main server configuration file to do configuration changes whenever possible. This is because when Apache is configured to process .htaccess files it looks at every directory underneath the current directory to see if there are any files present, resulting in a slightly longer page load time. Although this might not be noticeable with low traffic levels, at high traffic levels it can cause sites to slow down. You should therefore use .htaccess files only when the main server configuration file (http.conf) is inaccessible.

To increase performance you can use the AllowOverride directive in your top level directory, or any directory who's subdirectories do not use .htaccess files. This will stop Apache from searching through all sub directories.

Since starting programming I have used a lot of text editors, some have been good, and some have been very, very bad.

One text editor that stands out is PSPad. It is a free text editor for Windows that has lots of features and is very stable. I have been using this for a while now and have seen very little problems. I say "very little" as I once tried to open a 800 megabyte log file and it fell over, which is understandable.

It has the following features:

Use the following bit of code to create a web safe colour table. In order to for the name of each colour to be displayed the background colour array is reversed and used to create the foreground colours. This makes white text appear on black backgrounds and visa-versa, the only problem is that in the middle of the table it will display grey on grey.