The problem with supply chain attacks is specifically related to npm, and not related to JS. npm as an organization needs to be taking more responsibility for the recent attacks and essentially forcing everyone to use more strict security controls when publishing their dependencies.
It’s maybe a nit-pick, since most JS is run sandboxed, so it’s sort of equivalent. But it was explicitly what GP asked for. Would it be more accurate to say Electron is secure, not JS?
Any two Turing-complete programming languages are equally secure, no?
Surely the security can only ever come from whatever compiles/interprets it? You can run JavaScript on a piece of paper.
Conversely, barring a bug in the runtime or compiler, higher level languages don't enable those kinds of shenanigans.
See for example the heart bleed bug, where openssl would read memory it didn't own when given a properly malformed request.
Language design actually has a lot of impact on security, because it defines what primitives you have available for interacting with the system. Do you have an arbitrary syscall primitive? Then the language is not going to help you write secure software. Is your only ability to interact with the system via capability objects that must be provided externally to authorize your access? Then you're probably using a language that put a lot of thought into security and will help out quite a lot.
To be fair, a plugin system built on JS with all plugins interacting in the same JS context as the main app has some big risks. Anything plugin can change definitions and variable in the global scope with some restrictions. But any language where you execute untrusted code in the same context/memory/etc as trusted code has risks. the only solution is sandboxing plugins