How to read an input stream response coming from the API in nodejs

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Node.js

When i am trying to hit an API to read the file its giving me in input stream response, i need to convert that response either as a json object or into a file(xlsx) format.

Below is the code for calling the API,

var options = {
         host: 'xxxxxxx.xxxxx.com',
         port: xxxx,
         path: '/xxxxx/api/downloadFile?code=' + req.query.code,
        method: 'GET',
        headers:{ 
            'user_id': req.headers.user_id,
            'access_token': req.headers.access_token 
         }
      };
      var req = https.request(options, function (res) {
        var decoder = new StringDecoder('utf8');
        res.on('data', function(chunk) {
            console.log(chunk)
            var textChunk = decoder.write(chunk);
            console.log(textChunk)
        });
      });
      req.end();
      req.on('error', function(e) {
        console.error(e);
    });

What I have tried:

Tried to convert the response in buffer format and write into a file---but didnt work
As well tried to directly read the file from the API