I get a reference error when I try this (chrome stable on linux)

Ah, thanks for the heads-up, apparently there is something borked in Chromium wrt $ / $$ encapsulation, as it seems they are nor reachable from the (global) context setInterval so doing `window.$ = $; window.$$ = $$;` fixes that in Chrome. Not sure why. (Yet again embarrassed myself by trying a snippet that "simply must work ® according all documentations ™" in single a browser only before posting. Sigh.)

Filed as https://issues.chromium.org/issues/388437264

I bet it's working as intended. The $ symbol is probably a special feature of the console and is not intended to be a property of window. Inside setInterval, the function is no longer being executed in the special console environment, which has access to that symbol.

Yes, I guess there could be some intention behind that, presumably some security precautions, but still: the fact that you can see $ in the globalThis (as a non-enumerable prop), and that globalThis you see from inside the timeout-ed function is strictly equal to globalThis seen directly from the console, that makes it somewhat spooky.

    console.log(Object.getOwnPropertyDescriptor(globalThis, '$'))
    // {writable: true, enumerable: true, configurable: true, value: f}
    globalThis.globalThat = globalThis
    globalThat.$ === globalThis.$
    // true
    setTimeout(()=>console.log(globalThis.globalThat === globalThis))
    // true
    setTimeout(()=>console.log(Object.getOwnPropertyDescriptor(globalThis, '$')))
    // undefined (!)
    $ = $
    setTimeout(()=>console.log(Object.getOwnPropertyDescriptor(globalThis, '$')))
    // { writable: true, enumerable: true, configurable: true, value: f}

And it (`setTimeout(()=>{console.log(typeof $==="function")},0)`) works in Firefox. (Interestingly, you cannot get $'s descriptor in there, but you have it always available in timeout.)

Was closed as "Infeasible", i.e. wontfix.