In Mac OS neXt one can use AppleScript to ask Safari to "do" a Javascript.

> tell application "Safari"
> (do JavaScript "document.readyState" in document 1 of window id winID)
> end tell

It's likely that other browsers have the same kind of capability to run their Javascript engines when asked with some kind of interprocess request. Whether it's worthwhile here is another question unless you're just trying to figure out what the Javascript does so you can emulate it in, say, perl.

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