What encoding to save excel data in?

Question

JavaScript

Greetings!
There is a RestAPI that provides excel (xlsx) data as a request:

request.post( 
     rest_url+"/basecoefficient/getReport", { json: true, body: req.body.data, headers: { 
    'content-type' : "application/json; charset=utf-8",   'Authorization': "Bearer " + req.body.token } }
    , function(err, response, body)  {

    console.log(response.body)
    return res.json(response)

  });

Response.body receives excel data (xlsx) in UTF form:

PK\u0003\u0004\u0014\u0000\b\b\b\u0000\u000b�DN\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u000b\u0000\u0000\u0000_rels/.rels���j�0\f�_���8�`�Q��2�m��\u00014[ILb��ږ���.[K\n\u001b�($}�\u0007�v?�I�Q.���uӂ�h���\u001bx>=��@\u0015��p�H\u00

When saving data in the current format, the file does not open. the data is in UTF format. How to convert UTF encoding to excel (xlsx) recognizable format?

Answer 1

Apparently, you process binary data as json.
I would reconsider in principle downloading the report - I would not return data, but would return a link where you can download the file.
In general terms, your POST request builds an excel and saves it to the file system. The output is a link to it, it is given to the client.
The client follows the link (the redirect is the same, for example), the file is downloaded and deleted from the server.