babel-upgrade

A tool that tries to automatically update most dependencies, config files, and JavaScript files that require Babel packages directly to Babel 7 (and more in the future). Log when replacing out preset-es2015,16,17, latest as FYI. Figure out how to change nested .babelrcs into using "overrides" instead. Monorepo support. Modify other config files as we go. Add to the upgrade guide which parts are autofixable and the command (if we care enough to make this individually runnable too infrastructure-wise). May need to add a warning on any 3rd party plugins since they might not be compatible. Handle the differences in plugins in v7 for default/loose/spec. Should certain parts be generic (replace the string babel-register with @babel/register)? Could be in a Makefile or somewhere else.