Sounds like a rehash of this: https://www.w3schools.com/tags/tag_map.asp in JS, perhaps designed by someone unable to construct an adequate search engine query to solve the problem they thought they had but having access to a manual for JS. Compound that with the religious zeal that invariably (well - quite often) follows initiation into the sect around a newly discovered programming language. The manual may not actually exist but consist of a few links to Stackoverflow.

"Never attribute to malice that ..." as Mr Halon might say. I've found out later that I've re-invented the wheel with a system more than once (mine obviously sported Fandango tyres) and laughed at several other single axis rotation optimised load bearing solution implementations with minimised frictional components and thrust load resistance.

Experience is a wonderful thing - your's and theirs (and mine)

Cheers Jon