Winston Best Method.js

//----------------------------------Winston config file--------------------------------//

/*https://www.npmjs.com/package/winston*/
const winston = require('winston');

/*https://www.npmjs.com/package/bvalid*/
const bv      = require('bvalid');

const logpath = "/var/log/application_name";

const getFileDateTime = ()=>{
  var current_date = new Date();
  return current_date.getFullYear()+'_'+(current_date.getMonth()+1)+'_'+current_date.getDate();
}

const getFileName = (dir)=>{
  var _f = logpath;
  if(bv.isString(dir)){
    _f += dir + '/';
  }else{
    _f += 'application/'
  }
  return _f + getFileDateTime() + '.log';
}

var debug = (dir)=>{
  var _fn = getFileName(dir);
  return winston.createLogger({
      levels: {
        debug: 0
      },
      transports: [
        new (winston.transports.File)({ filename: _fn, level: 'debug'}),
        new (winston.transports.Console)({level: 'debug'})
      ]
    });
}

var info = (dir)=>{
  var _fn = getFileName(dir);
  return winston.createLogger({
    levels: {
      info: 1
    },
    transports: [
      new (winston.transports.File)({ filename: _fn, level: 'info'}),
      new (winston.transports.Console)({level: 'info'})
    ]
  });
}

var warn = (dir)=>{
  var _fn = getFileName(dir);
  return winston.createLogger({
    levels: {
      warn: 2
    },
    transports: [
      new (winston.transports.File)({ filename: _fn, level: 'warn'}),
      new (winston.transports.Console)({level: 'warn'})
    ]
  });
}

var error = (dir)=>{
  var _fn = getFileName(dir);
  return winston.createLogger({
    levels: {
      error: 3
    },
    transports: [
      new (winston.transports.File)({ filename: _fn, level: 'error'}),
      new (winston.transports.Console)({level: 'error'})
    ]
  });
}

var exports = {
  debug: function(msg,dir){
    debug(dir).debug(msg);
  },
  info: function(msg,dir){
    info(dir).info(msg);
  },
  warn: function(msg,dir){
    warn(dir).warn(msg);
  },
  error: function(msg,dir){
    error(dir).error(msg);
  },
  log: function(level,msg,dir){
    var lvl = exports[level];
    lvl(msg,dir);
  }
};

module.exports = exports;
//------------------------------------------------------------------------------------//


//---------------------------------Usage in another file-------------------------------//

var logger = require('path_to_winston_config");
logger.debug("message","dirname"); //is no dir name it will save in application folder in logpath
//or
/*         |level| |message| |dirname| */
logger.log("error","message","dirname");
//------------------------------------------------------------------------------------//