npm-pkginfo-cli/lib/get-pkg/src/terserrc.json

Command line utility to view info about your current package

{
  "compress": {
    "arrows": true,
    "arguments": true,
    "booleans": true,
    "ecma": 8,
    "keep_fargs": true,
    "keep_classnames": true,
    "keep_fnames": true
  }  
}