The babel documentation says it's a bad idea to do this in production, so I'm thinking of using webpack to transpile then entire back-end to one ES5 file. Do you know enough about this situation to tell me if this is a bad idea or not? Because obviously your approach would be 'simpler'.
Edit: An additional reason to transpile to ES5 is that on the whole much of the ES6 support is not very performant yet. While this might not matter for incidental uses of, say, template strings, it might become noticeable for an entire project. Or is that a clear case of premature optimization?
There's no difference in compiling to ES5 versus hooking into the module loading mechanism to compile on the fly, in terms of the end-result. The only practical difference is that precompiling means your modules will load faster the first time, but there will be no difference for subsequent loads since modules are cached. I'm guessing the caveat for running something like babel-register in production is the first-load performance penalty, as well as having less control over the compilation process. However, if you are ok with configuring babel through .babelrc files alone, and you're ok with the first-load performance penalty, I don't see what it'd be any worse than precompiling to ES5. (There may be subtle differences in debugging due to the lack of source maps, but I don't know enough to comment on that with any degree of certainty.)
That's informative, thanks. At least I have something to look into, and a quick search indicates that source maps are not even necessary in this approach!
Edit: An additional reason to transpile to ES5 is that on the whole much of the ES6 support is not very performant yet. While this might not matter for incidental uses of, say, template strings, it might become noticeable for an entire project. Or is that a clear case of premature optimization?