It works everywhere (it’s now specified in https://html.spec.whatwg.org/multipage/nav-history-apis.html#named-access-on-the-window-object https://html.spec.what

It works everywhere (it’s now specified in https://html.spec.whatwg.org/multipage/nav-history-apis.html#named-access-on-the-window-object https://html.spec.whatwg.org/multipage/nav-history-apis.html...), but it’s brittle. It can break by adding colliding properties to window deliberately or by accidental global leak (… including things like setting in dev tools), by browser defining new globals, by some 'name' attribute conflict.