I understand source maps are optional...not getting the exclamation point. That's exactly my point, it's optional and therefore not much help.

Minified js isn't (so far) a barrier for me. Prettify and a short bit of debug clears things up. Chrome even helps[1]. I have not yet run into asm.js used for anything in my field.

[1] https://developers.google.com/web/tools/chrome-devtools/java...