How to encode output json data with charset windows1251 using node.js API?

I want to encode the data to windows1251.

My output json data is not good like that:

API

This is my node.js API code:

    // Create express app
var express = require("express")
var app = express()
var mysql = require('mysql')
var express = require("express")
var cors = require('cors')

app.use(cors())

const utf8 = require('utf8');


// Server port
var HTTP_PORT = 3002

var pool = mysql.createPool({
  connectionLimit: 10,
  host: '',
  user: '',
  port: '',
  password: '',
  database: '',
  charset: 'cp1251_bulgarian_ci'
});

var HQdataAHS = '';
var HQstationsAHS = '';

function formatDate(date) {
  var d = new Date(date),
    month = '' + (d.getMonth() + 1),
    day = '' + d.getDate(),
    year = d.getFullYear();

  if (month.length < 2)
    month = '0' + month;
  if (day.length < 2)
    day = '0' + day;

  return [year, month, day].join('-');
}

var dateNow = formatDate(Date());

app.route('/HQstationsAHS')
  .get(function (req, res) {
    // omitted
    res.setHeader('Access-Control-Allow-Origin', '*', 'Cache-Control', 'private, no-cache, no-store, must-revalidate');
    pool.query(`SELECT Station, Ime FROM auto_q_stations;`, function (error, result2, fields) {
      if (error)
        return res.status(500).json({ error: "Грешна заявка. Опитай отново !" })
        HQstationsAHS = result2.map((item) => {
          item.Ime = utf8.encode(item.Ime);
          return item;
        });
    
       res.json({ HQstationsAHS })
     });
    });


// Start server
app.listen(HTTP_PORT, () => {
  console.log("Server running on port %PORT%".replace("%PORT%", HTTP_PORT))
});

pool.on('error', function (err) {
  console.log(err.code); // 'ER_BAD_DB_ERROR'
});

app.use(function (req, res) {
  res.status(404);
});

I installed from npm windows1251 library from here:

https://www.npmjs.com/package/windows-1251

After installation I try to encode this line like that:

item.Ime = utf8.encode(item.Ime);

item.Ime = windows1251.encode(item.Ime);

But I receive error: windows1251 is not defined..

How to encode my output json data to windows1251 ?