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If you are running a JavaScript example page you can use the following function that will take the last script element on the page and print it out in a code tag. It uses JQuery to do the work, so you will need to include that library before using this function.

The isNaN() function (NaN stands for Not a Number) can be useful if you are looking at form inputs or similar and is used to detect if a value is not a number. For example, the following code shows the output of isNaN() on two variables.

var number42 = "42";
var wibble = "wibble";
alert(isNaN(number42)); // Prints out false
alert(isNaN(wibble)); // Prints out true

This first test is true because the number 42 is, in fact, a number. The second test is false because wibble isn't a number. This is simple enough, but what if we started looking at some different values?

Sometimes, especially when moving data from one server to another, you might find that you have encoded your MySQL database incorrectly. This problem with first show itself if you have the database encoded in one charset and your website set to display in another. If this is the case then you will find strange characters appearing in your text, especially when using punctuation marks. If you are unable or unwilling to change the character encoding on the site then you need to change how the data is encoded in the database.

The most common sort of thing you might want to do is change from iso-8859-1 (or windows-1252) to UTF-8. This can be done in one of two ways.

The first way is to simply alter the table so that the column contains a different charset.

Strictly speaking the Google Ajax libraries don't contain only Ajax libraries, but they are very useful for a variety of reasons. Google host a variety of different JavaScript libraries which you can link to on your pages rather than download the library and host it on your server. You can use MooTools, JQuery, Prototype/Scriptaculous, Dojo and even the Yahoo! User Interface Library.

How To Use Them

Using the Google Ajax libraries on your own site is quite easy, and you can do it in a number of different ways.

Normally, you would download the latest and greatest version of your chosen library and upload it to your site. Here is an example using the MooTools.

<script type='text/javascript' src='http://www.hashbangcode.com/mootools.js'></script>

You can include this via Google using the following.

JS Bin is an online tool that allows you to test JavaScript without having to muck about with files. You can just quickly cut and paste some code in and view the output. It is even possible to make the code you are looking at public and then use this as part of an ajax call in another instance of the application.

To get you started there is a nice help section, which also includes a couple of videos.

This tool really impressed me, especially the easy inclusion of several different JavaScript frameworks. I don't mind testing JavaScript, but sometimes I just want to run a little bit of code on it's own to see why it isn't working as I expected it would. This tool fills that much needed gap, and the addition of allowing other people to view your code is a very nice feature. Well worth a look!

There are two main ways in which to redirect the browser using JavaScript, both of which look at the location of the window object. These are the location.href property and location.replace function.

location.href

The following example will cause the page to redirect to another page, keeping the browser history. This might seem like a minor point, but if you redirect a user to another page they will be able to click back, which will mean that they are redirected again.

Using server side scripts to search for things can be as complex or as simple as the situation requires. However, if you have a table of results and you just want to enable a simple JavaScript search on that table then this might be the script for you.

To search a table using JavaScript you need to split the table into bits, this can be done using the getElementsByTagName() function, which takes the name of the element that you want to capture. So to grab all of the rows of a table as an array you need to pass the value of tr.

var rows = document.getElementsByTagName("tr");

We can then iterate through these rows, grabbing the column that you want to search on, with the following code.

Run the following table definition to create a table called tests in the test database.

DROP TABLE IF EXISTS test.tests;
CREATE TABLE test.tests (
 id int(10) unsigned NOT NULL auto_increment,
 var varchar(45) NOT NULL,
 PRIMARY KEY  (id)
);

Fill it with some default values:

INSERT INTO tests(var) VALUES('one'), ('two'), ('three'), ('four');

Now lets say that you want to find the values in the table, but that you want to increment a value for each row, the following procedure will do this. If you are using the MySQL Query browser then open a script table and past the following and execute, changing any database/table definitions.

If you are part of a company the chances are that you have either set up or are aware of a backup policy for your data. However, even if you are not then you might have the need to backup certain items to a DVD drive.

DVD burning is accomplished in Linux by using the mkisofs and growisofs programs. This can be run in either a two stage or a single stage process. The mkisofs program is used to create an iso file that is then written to the DVD using the growisofs program. The following will take three files and create an iso called toburn.iso, this will then be used to write the data to the DVD.

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