How to format a bash array as a JSON array

Question

I have a bash array

X=("hello world" "goodnight moon")

That I want to turn into a json array

["hello world", "goodnight moon"]

Is there a good way for me to turn this into a json array of strings without looping over the keys in a subshell?

(for x in "${X[@]}"; do; echo $x | sed 's|.*|"&"|'; done) | jq -s '.'

This clearly doesn't work

echo "${X[@]}" | jq -s -R '.'

Answer 1

You can do this:

X=("hello world" "goodnight moon")
printf '%s\n' "${X[@]}" | jq -R . | jq -s .

output

[
  "hello world",
  "goodnight moon"
]

Answer 2

This ...

X=("hello world" "goodnight moon" 'say "boo"' 'foo\bar')

json_array() {
  echo -n '['
  while [ $# -gt 0 ]; do
    x=${1//\\/\\\\}
    echo -n \"${x//\"/\\\"}\"
    [ $# -gt 1 ] && echo -n ', '
    shift
  done
  echo ']'
}

json_array "${X[@]}"

... yields:

["hello world", "goodnight moon", "say \"boo\"", "foo\\bar"]

If you are planning to do a lot of this (as your reluctance to use a subshell suggests) then something such as this that does not rely on any subprocess is likely to your advantage.