I'm the author and I can confirm. The website will not work with JS disabled simply because it's a static HTML "skeleton" page loading JSON tables with JS and populating a <table> element. If it's working then it means you must have JS enabled. I don't plan to add support for browsers without JS, but the JSON tables have all the information you need anyway, and those are just static files (e.g. https://syscalls.mebeim.net/db/x86/64/x64/latest/table.json).