catj

json-flatten-js.jq

#!/usr/bin/jq -jf

# Original Author: jolmg on HN (https://news.ycombinator.com/item?id=20246727)
#
# 
#
# Author notes:
# You whitelist against what the syntax allows for identifiers and then you blacklist reserved keywords. 
# Writing it this way makes it easier to verify for correctness when comparing with the ECMAScript Specs. 
# This is still a non-exhaustive blacklist and the whitelist regex lacks allowed unicode characters.
# https://news.ycombinator.com/item?id=20246727

jq -r '
  tostream
  | select(length > 1)
  | (
    .[0] | map(
      if tostring | (
        test("^[A-Za-z$_][0-9A-Za-z$_]*$")
        and (
          . as $property
          | ["if", "else"] | all(. != $property) 
        )
      )
      then "." + .
      else "[" + @json + "]"
      end
    ) | join("")
  ) + " = " + (.[1] | @json)
'