Using Division Equations to Make Web Forms Safer with Ajax
From a web developer’s point of view, building a mechanism that permits you to protect online forms against attacks by spam bots, malicious automated submissions, and so forth, can be challenging. Developing such an application often requires using a server-side graphic library to generate the so-called noisy images. However, it’s possible to quickly create a similar mechanism with Ajax, without having to work directly with images generated in the web server. This is the fourth part of a four-part series that explains how to do just that.
Therefore, if you’re interested in learning how to build a basic Ajax-driven program that makes your web forms a bit more secure, then in this group of articles you’ll have at your disposal a comprehensive guide on how to achieve this with minor efforts. Additionally, you’ll learn how to provide the program in question with the capacity for generating different types of mathematical operations in the form of challenge strings.
And speaking of mathematical operations, you’ll probably recall that during the previous article of the series, I demonstrated how to develop a simple Ajax-based system that could display multiplication equations within a targeted online form.
In this particular case, before submitting the online form, users were asked to enter the correct result of this operation, which was properly checked in the web server at a later time. Of course, as you may guess, this approach has some disadvantages, since those dynamic operations are embedded into the web form as plain text, which can be pretty easy to digest for some web bots. However, this protecting mechanism is extremely simple to implement, and it can be also used when working with online forms that don’t collect critical data.
In this fourth part of the series, I’m going to teach you how to adapt the Ajax application developed in the previous article, so it can display division equations as challenge strings into a selected online form.
Thus, with the preliminaries out of our way, it’s time to learn how to create the aforementioned Ajax program in a few simple steps. Let’s begin now!
AJAX & Prototype 
