Frequency response of the amplification stage (20th century retro script)

In accordance with the declaration that I am reproducing the content of a long-defunct Fonar website in this section, I am posting, without any changes or modifications, a script for calculating the lower and upper cutoff frequencies of a tube amplifier stage. This script, like others marked as "Retro Scripts," was created by modifying a so-called applet I wrote in the 1990s and added to the Fonar website in the early 21st century. From a modern JavaScript perspective, it contains many unused elements. From a practical perspective, the script's advantages are limited, as we currently have programs for simulation calculations. It can be used by anyone who wants to perform quick calculations without even implementing such a simple circuit. The script may also be interesting for someone who programs in JavaScript and would like to see what a script written a quarter of a century ago looks like.

Please note that due to the program's age, you may experience problems running it in some browsers. I don't experience any. I invite you to view, try, and analyze the source code:

Frequency response of the amplification stage