As an amateur web builder, I had to face such a non-trivial task (for an amateur) as creating various kinds of calculators, so that a user could calculate the cost of a UFO in a couple of clicks on web form elements.
“Ugh, business!” - exclaim many of the readers who are familiar with JavaScript, like Ilya Kovalchuk with a stick and puck. But personally, I exclaimed: “P & $ de $ how much business” and my inflamed brain rushed to search for a way out:
1. To order the manufacture of such a calculator (this is a time cost and I suspect so much money). This option is rejected immediately, because the project is absolutely not commercial and for the soul, and honestly to say: "the toad strangled."
2. Examine JavaScript and gracefully write a script. What I actually began to do on the quiet, but it turns out to learn JavaScript it needs to be taught and practiced.
3. The most optimistic option is to search for software with similar functionality to generate the required code.
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It is not strange, but such software was discovered by me at the stage of open beta testing.
and from that moment I became actively involved in this process, and so meet:
The release of the 3rd version took place the other day. And now we have a simple tool for creating this kind of web services.

With a banal construction of web forms, this softphone copes with a bang in WYSIWYG mode, but on the main highlight, namely the
Calculated Field, I will allow myself to stop:
The field with the results of calculations is added simply, like any other field:

In the field properties, we simply write the formula:

On the left we throw in the fields from which the value values are taken.
Right functions: there are logical (
if_else - if_to.
Map_to_number - assigning numbers to text values of checkboxes and radio
dots .
Is_checked - assignment 1 if the checkbox or radio
point is selected and 0 if not), mathematical (arithmetic, trigonometric, etc.) and working with dates.
In addition, the software is
very flexible and customizable validator of the input data, and it is possible to fasten the already existing forms.
Scripting requires a server with PHP support of at least 4.3.0
The program itself is written to work under Win.
There is an interesting note in the
author's blog , as the masters of the epistolary genre to legally get the key.
Unfortunately, for the time being, my considerations on processing text values have not been included in the release. But, "haircut just started."
PS I hope that this software will make life easier for the creators of such web services.