Of course _.each handles objects (not just arrays) and returns its input (where Array#forEach returns undefined), and there does not seem to be any type-based conditions (or otherwise) so you've got a souped-up sed, not something you can add to any sort of automated workflow.
Also go fmt doesn't ever change your code, thats what go fix is for.
JsFmt also works on the AST. Working on the AST does not mean your rewrite rules can be bulletproof, let alone are.
> Javascript formatters exist but most (all?) work on just strings, not the AST. Using Esprima under the hood we have access to the full AST and can do useful things like intelligent find and replace as in gofmt.