How to append a json variable to another?

Question

I want to avoid using JSON files and use variables but it doesn't work

element='{"x": "zero"}'
example='{
    "a": "one",
    "b": "two",
    "c": "three",
}'

jq -s '.[0] * .[1]' element.json example.json

If the contents of the JSON files are exactly as what's inside the single quotes of the vars it works as expected. But I also want the element to be the first one (with * it doesn't go first, with +=, it makes another object)

If I replace the filenames with $element and $example, it fails (expecting a file)

I tried like this:

jq --argjson el "$element" --argjson ex "$example" '$el += $ex'

but it says jq: invalid JSON text passed to --argjson. I don't get it. The vars seem to be correct JSON.

I just want this output, "x" first, using variables not files:

{
    "x": "zero",
    "a": "one",
    "b": "two",
    "c": "three",
}

Answer 1

It worked using the comment suggestions like this

element='{"x":"zero"}'
example='{
    "a":"one",
    "b":"two",
    "c":"three"
}'
jq -n --argjson el "$element" --argjson ex "$example" '$el + $ex'