How to change timezone in Winston timestamp ? Node js

How can I change the timezone in this code? I tried some codes but it was not successful for me. I wrote some function for this. For example:

const timezoned = () => {
    return new Date().toLocaleString('en-US', {
      timeZone: 'Europe/Istanbul'
    });

This is my code:

const winston  = require('winston');
const { format, level, prettyPrint } = require('winston');
require('winston-daily-rotate-file');
 
  var transport = new (winston.transports.DailyRotateFile)({
    filename: 'application-%DATE%.log',
    datePattern: 'YYYY-MM-DD-HH',
    zippedArchive: true,
    maxSize: '1g',
    format:format.combine(format.timestamp(),format.prettyPrint()),
    level: 'info'
  });
 
  transport.on('rotate', function(oldFilename, newFilename) {
    // do something fun
  });
 
  var logger = winston.createLogger({
    transports: [
      transport
    ]
  });
 
  };
  module.exports.logger = logger;
 

You can pass a format value to the timestamp formatter, this can be a string or a function.

The details are here: https://github.com/winstonjs/logform#timestamp

So we can use your timezoned function and the times will be in Europe/Istanbul time, though formatted as US (because of the 'en-US' locale, you can obviously change this as you wish).

const winston  = require('winston');
const { format, level, prettyPrint } = require('winston');

const timezoned = () => {
    return new Date().toLocaleString('en-US', {
        timeZone: 'Europe/Istanbul'
    });
}

require('winston-daily-rotate-file');

var transport = new (winston.transports.DailyRotateFile)({
    filename: 'application-%DATE%.log',
    datePattern: 'YYYY-MM-DD-HH',
    zippedArchive: true,
    maxSize: '1g',
    format:format.combine(format.timestamp({ format: timezoned }),format.prettyPrint()),
    level: 'info'
});

transport.on('rotate', function(oldFilename, newFilename) {
    // do something fun
});

var logger = winston.createLogger({
    transports: [
    transport
    ]
});

module.exports.logger = logger;

The output will look like this:

{
    message: 'Log test',
    level: 'info',
    timestamp: '7/16/2020, 12:34:40 PM'
}