Using Self-Modifying Code in JavaScript

When I started working in Information Technology (over 25 years ago), I met a guy named Dave who had been at the large insurance company (where I accepted employment) for a few years.  Dave’s job focused on program code supporting a core product called “Individual Life Insurance."  If you bought a personal life insurance policy from an agent representing this company, Dave’s code was running in the background to support the needs of that business line.
One of our initial conversations was regarding a task he had recently completed.  That task was to remove all the self-modifying code that was running for years on the mainframe system which handled the individual life insurance family of products. For those who are not aware, self-modifying code is defined by Wikipedia as: