fs wouldn't be expected to work in a web page, Fuse's approach to JS is the same. In short: you'll have greater success with Fuse (and more fun!) if you approach it as a new thing rather than a typical DOM-based JS framework. :)
With that in mind, this chapter contains a list of libraries that are known to work/not work, and explains workarounds/caveats.
This list will be expanded as FuseJS develops.