How can I add timestamp to logs using Node.js library Winston?

Question

I want to add timestamp to logs. What is the best way to achieve this?

Answer 1

We can do like this also

var winston = require('winston');
const { createLogger, format, transports } = require('winston');
var config = require('../configurations/envconfig.js');

var loggerLevel = process.env.LOGGERLEVEL ||  config.get('LOGGERLEVEL');

var logger = winston.createLogger({
  format: format.combine(
    format.timestamp({
      format: 'YYYY-MM-DD HH:mm:ss'
    }),
    format.printf(info => `${info.timestamp} ${info.level}: ${info.message}`+(info.splat!==undefined?`${info.splat}`:" "))
  ),
  transports: [
    new (winston.transports.Console)({ level: loggerLevel }),
  ]
});
module.exports = logger;

Answer 2

Another solution is wrapping the logger into a file that exports some functions like logger.info(), logger.error(), etc. then you just pass an extra key to be sent on every message log.

loggerService.js

const logger = winston.createLogger({ ... })

function handleLog(message, level) {
  const logData = {
    timestamp: Date.now(),
    message,
  }

  return logger[level](logData)
}

function info(message) {
  handleLog(message, 'info')
}

function error(message) {
  handleLog(message, 'error')
}

function warn(message) {
  handleLog(message, 'warn')
}

module.exports = {
  info,
  error,
  warn
}

whatever-file.js

const logger = require('./services/loggerService')

logger.info('Hello World!')

your-log.log

{"timestamp":"2019-08-21 06:42:27","message":"Hello World!","level":"info"}

Answer 3

Above answers did not work for me. In case you are trying to add timestamp to your logs using the latest version of Winston - 3.0.0-rc1, this worked like charm:

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

    const logger = createLogger({
        format: format.combine(
            format.timestamp(),
            format.json()
        ),
        transports: [
            new transports.Console(),
            new transports.File({filename: 'logs/error/error.log', level: 'error'}),
            new transports.File({filename: 'logs/activity/activity.log', level:'info'})
        ]
    });

I used 'format.combine()'. Since I needed timestamp on all my transports, I added the formatting option within the createLogger, rather than inside each transport. My output on console and on file (activity.log) are as follows:

{"message":"Connected to mongodb","level":"info","timestamp":"2018-02-01T22:35:27.758Z"}
{"message":"Connected to mongodb","level":"info","timestamp":"2018-02-01T22:35:27.758Z"}

We can add formatting to this timestamp in 'format.combine()' as usual using:

format.timestamp({format:'MM-YY-DD'})