Ajax :: Use PHP With Files On Localhost?

For Ubuntu 10.04, Apache 2, PHP5 and MySQL 5, Firefox 3.6. (I already had Apache, Mysql and Firefox installed, so only added PHP5 via the synaptic manager a couple of days ago).

I have only just started with Ajax and PHP and obtained some demo files from w3schools.com (by googling on 'Ajax PHP database') that I named w3.html and getuser.php. These show how to find person details in a MySQL data base and send them back to be displayed by a browser. They work when Firefox accesses the demo at w3schools.com.

I put these files into directory /var/www on my PC (the upload file directory) and tried via Firefox, but got this error showing in the Firefox Error console:

I also obtained a similar demo from [url]. It failed in the same way, but worked when accessing www.tizag.com directly.

I googled on permutations of 'Ajax', 'XMLHTTPRequest' and 'no element found' and noticed that many have had this problem. A few said that this problem occurs when the Ajax-side expects XML but gets HTML from the server, but did not give any solutions.

PHP works when I put 'localhost/getuser.php?q=2' into the Firefox addressbar. It generates the result table which looks well-formed to me.

I then modified the eventhandler onreadystatechange to

Code:

And found:

i) The status code returned is always 0 (not 200 or any other 3-digit http return code).

ii) The text returned is the content of the getuser.php file, not the content generated by executing the PHP code.

iii) The 'no element found' error is still shown

My intention was to learn and experiment with Ajax and PHP on my local PC, but it did not work. Can it be done, or do I have to get a website and use FTP to upload?

w3.html

Code:

w3.html:

Code:

Use mysql command source w3demo.sql from the MySQL command line.