jsonb manipulator based on https://gist.github.com/matheusoliveira/9488951

jb.sql

CREATE FUNCTION jb_merge(jsonb, jsonb)
RETURNS jsonb
IMMUTABLE
LANGUAGE SQL
AS $$
  WITH xxx AS
    (SELECT * FROM jsonb_each_text($1)
       UNION ALL
     SELECT * FROM jsonb_each_text($2))
  SELECT json_object_agg(key, value)::jsonb FROM xxx;
$$;

CREATE FUNCTION jb_add(jsonb, text, text)
RETURNS jsonb
IMMUTABLE
LANGUAGE SQL
AS $$
  SELECT jb_merge($1, json_build_object($2, $3)::jsonb);
$$;

CREATE FUNCTION jb_add_pairs(jsonb, variadic text[])
RETURNS jsonb
IMMUTABLE
LANGUAGE SQL
AS $$
  SELECT jb_merge($1, json_object($2)::jsonb);
$$;

CREATE FUNCTION jb_delete(jsonb, variadic text[])
RETURNS jsonb
IMMUTABLE
LANGUAGE SQL
AS $$
  SELECT json_object_agg(key, value)::jsonb
  FROM (
    SELECT * FROM jsonb_each_text($1)
    WHERE key <> ALL($2)
  ) t;
$$;