Get Form data in json format

I am having issue while fetching form data in serverless functions.
As its giving me output of “event.body” as

------WebKitFormBoundary6mmABEnOgWqEyxYH
Content-Disposition: form-data; name="test"

12345
------WebKitFormBoundary6mmABEnOgWqEyxYH--

I want this data in JSON format so that i can use it.

Please let me know the solution for this