Am I missing something, but wouldn't that require pasting the 49mb file into your app through my clipboard? Just getting a file like that into the clipboard, let alone pasting into the browser, seems like a task in itself.
All it does is JSON.parse, execute your series of functions then JSON.stringify.
Unless I'm missing something there is no advantage over ad-hoc javascript. If you want to load a file from disk, deserialize and do some processing in javascript then node is absolutely the right tool (and this isn't).