what is the equivalent of python open(filepath, ‘rb’) in JavaScript

I can open the file in binary mode with Python and store it in a variable.
I have been researching this for two days, and I can’t seem to find a straightforward answer. I need this because I have been working on a project that we have completed in Python, but we need to convert it into JavaScript. The issue that I’m having is that I need to send a file through an API call. Still, every time I do, I get this error ‘ HTTP 415 Unsupported Media TypeThe provided media type is not supported for the requested URI. What I have is a JSON file that I need to pass to a post-call in binary

files = {'file': open(JSON_File, 'rb')}
response = requests.post(
    URL, 
    auth=(USERNAME, PASSWORD),
    files=files
    #files=files, verify = False
)

response.text

how can I do this in nodeJS? I completed the above already in Python.