Inside the Calculators – Part III – AJAX

I recently gave a brief overview of my permanent disability and workers’ compensation benefit calculators. In that post I wrote a little bit about how my online benefits calculators work. Since then I’ve posted about my use of javascript and PHP in creating these permanent disability and permanent impairment calculators.

As I’ve mentioned in those prior posts, both javascript and PHP have inherent downsides. My very first attempt at online benefits calculators using javascript and ASP actually suffered from all of the downsides of javascript and PHP. Those first calculators used tons of user’s computers’ resources, bandwidth, and server power. However, learning more about AJAX enabled me to build a set of calculators which benefited from the strengths of javascript and PHP while minimizing, if not eliminating, their weaknesses.

The acronym “AJAX” refers to “asynchronous javascript and XML” – a collection of other technologies which allow a webpage to communicate with a web server without requiring an entire page download.

Example 1: A calculator without AJAX calculating “6 x 7” would send information to be calculated to the web server. The web server would then respond by giving you an entirely new page with the answer, “42”. However, in order to download that answer you would need to download a whole new page – and all the images, text, and code associated with it. Even a normal web page could be between 30,000 and 300,000 bytes in size.[1]

Example 2: A calculator with AJAX calculating “6 x 7” would send information to be calculated to the web server. The web server would then respond by sending back just the answer, “42”. This would be 2 bytes.

If my calculators needed to download of 300 kilobytes for every single operation, a simple calculation could take about 30 seconds on dialup and a full 1 second on broadband. Although 1 second doesn’t seem like a long time – it is in the internet age. Most of the calculations on this site take approximately .500 seconds using a broadband connection. I would guess that about 90% of that time is due to network latency/network lag – which wouldn’t be much different for a dialup connection.

For the first few months after the launch of this website, it did not use a MySQL database. I actually went to some pretty ridiculous extremes to not have to learn a new programming language. I eventually gave in, learned how to use MySQL and am a better programmer for it.

Next up, MySQL!

  1. A download of “” was approximately 30,000 bytes and a download of “” was approximately 300,000 bytes. []

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