Finding if each element of array 1 exists in array 2

I have 2 json files: a_names.json and b_names.json.
File a:

Finding if each element of array 1 exists in array 2

I have 2 json files: a_names.json and b_names.json.
File a:

jq returns null or error when parsing json response

When parsing a json response using jq run from cmd.exe on a Windows 10 machine, I always get either a null response or an error when trying to get a value present in the JSON.

Convert JSON array of key/value pairs into values with a comma seperator using jq

I have the following JSON.