winston logger implementation in node.js

util.winston.js

/**
 * dependencies
 * "moment-timezone": "^0.5.23",
 * "winston": "^3.2.1"
 */

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

var util = {
  _loggers: {},
  /**
   * like the above but instead, this logs to file
   *
   * sample usage:
   * 
   * util.logf('debug-leakance','example-'+util.randstring(4, util.rand(5,16)));
   * util.logf('debug-duodecimo','example-'+util.randstring(4, util.rand(5,16)));
   * util.logf('debug-undefied','example-'+util.randstring(4, util.rand(5,16)));
   * util.logf('debug-burring','example-'+util.randstring(4, util.rand(5,16)));
   * util.logf('debug-lux','example-'+util.randstring(4, util.rand(5,16)));
   */
  logf: function(type, message, level){
    var level = level === undefined ? "info" : level;

    if(Array.isArray(message))
      message = JSON.stringify(message)
    else if(typeof message === 'object')
      message = JSON.stringify(message)

    var theLogger = null;
    if(util._loggers[type] == undefined){
      theLogger = createLogger({
        format: format.combine(
          format.printf(info => util.winstonMomentWrapper() +` ${info.level}: ${info.message}`+(info.splat!==undefined?`${info.splat}`:" "))
        ),
        transports: [
          new (transports.File)({
            filename: `./traces/${type}.log`,
            json: false,
            maxsize: 10000000, // 10MB
            maxFiles: 1
          })
        ]
      });

      util._loggers[type] = theLogger;
    }else{
      theLogger = util._loggers[type];
    }

    theLogger.log(level, message);
  },
  winstonMomentWrapper: function(){
    return util.moment(null, { 
      format: "YYYY-MMM-DD h:mm:ss.SA",
      timezone: "Asia/Manila"
    });
  },
  /**
   * get a moment instance pre-configured
   * @param  string datetime     nullable
   * @param  Object customParams 
   *         { 
   *           // null if you prefer application timezone
   *           timezone: "America/Los_Angeles", 
   *           
   *           // null if you prefer the default format of momentJS
   *           format: "MMMM Do YYYY, h:mm:ss a", 
   *         }
   * @return {[type]}              [description]
   */
  moment: function(datetime, customParams){
    if(datetime === null)
      datetime = undefined;

    var myMoment = moment(datetime);

    if(customParams === undefined)
      customParams = {};

    if(customParams.timezone !== undefined){
      myMoment.tz(customParams.timezone);
    }else{
      myMoment.tz(config.app.timezone);
    }

    if(customParams.format !== undefined){
      return myMoment.format(customParams.format);
    }else{
      return myMoment;
    }
  }
}

module.exports = util;