Custom Logger Library with winston

log.js

const { createLogger, format, transports } = require('winston')
const moment = require('moment')

// set default log level.
const logLevel = 'info'

var logger = createLogger({
  level: logLevel,
  levels: {
    fatal: 0,
    crit: 1,
    warn: 2,
    info: 3,
    debug: 4,
    trace: 5
  },
  format: format.combine(
    format.prettyPrint(),
    format.timestamp({
      format: 'DD-MM-YYYY hh:mm:ss A'
    }),
    format.printf(nfo => {
      return `${nfo.timestamp} - ${nfo.level}: ${nfo.message}`
    })
  ),
  transports: [
    new transports.Console(),
    new transports.File({
      filename: 'bot.log'
    })
  ]
})

// Extend logger object to properly log 'Error' types
var origLog = logger.log

logger.log = function (level, msg) {
  if (msg instanceof Error) {
    var args = Array.prototype.slice.call(arguments)
    args[1] = msg.stack
    origLog.apply(logger, args)
  } else {
    origLog.apply(logger, arguments)
  }
}
/* LOGGER EXAMPLES
  var log = require('./log.js')
  log.trace('testing')
  log.debug('testing')
  log.info('testing')
  log.warn('testing')
  log.crit('testing')
  log.fatal('testing')
 */

module.exports = logger
=

var logLevel = 'info' // Winston will log info and lower than info log level.

So log.trace('testing') and log.debug('testing') will not be log by winston.

If you want to log trace and debug then set var logLevel = 'trace'

how to connect this logger.js in my default app.js in express js and i want console entire log data in one text file

FYI, this does not work with 3.x version of logger. check this for 3.x version - https://gist.github.com/aabrapp/984834cf319a2c6e965cacc52caccde8

@aabrapp I have updated for 3.x Version.

somehow trace is not working

also it doesnot write the logs into the bot.log

I have corrected the code , write logs into the respective file

const fs = require('fs');
const {
  createLogger,
  transports,
  format
} = require('winston');

const env = process.env.NODE_ENV;
const logDir = 'logs';

if (!fs.existsSync(logDir)) {
  fs.mkdirSync(logDir);
}

const now = new Date();
const logLevel = 'info'

var logger = createLogger({
  level: logLevel,
  levels: {
    fatal: 0,
    crit: 1,
    warn: 2,
    info: 3,
    debug: 4,
    trace: 5
  },
  format: format.combine(
    format.prettyPrint(),
    format.timestamp({
      format: 'DD-MM-YYYY hh:mm:ss A'
    }),
    format.printf(nfo => {
      return `${nfo.timestamp} - ${nfo.level}: ${nfo.message}`
    })
  ),
  transports: [
    new transports.Console(),
    new transports.File({
      filename: `${logDir}/app.log`,
    })
  ]
})

// Extend logger object to properly log 'Error' types
var origLog = logger.log

logger.log = function (level, msg) {
  if (msg instanceof Error) {
    var args = Array.prototype.slice.call(arguments)
    args[1] = msg.stack
    origLog.apply(logger, args)
  } else {
    origLog.apply(logger, arguments)
  }
}

module.exports = logger;

module.exports.stream = {
  write: function (message) {
    logger.info(message);
    console.log('message = ', message);
  },
};

hi, look for the same and this is useful.
questions:

1. what is the module.exports.stream for? how to use it?
2. is it possible to capture the caller file, caller function or line number?

thanks!

Working perfect for me. Tks