Log4js examples

accesslogger.js

const log4js = require('log4js');
const logger = require('./logger').access;

module.exports = function(options) {
  options = options || {};
  options.level = options.level || 'auto';
  return log4js.connectLogger(logger, options);
};

logger.js

const log4js = require('log4js');
const levels = require('log4js/lib/levels').levels;
const config = require('../../config/log4js.config');
let console, system, application, access;

log4js.configure(config);

console = log4js.getLogger();

system = log4js.getLogger('system');

const ApplicationLogger = function() {
  this.logger = log4js.getLogger('application');
};
let proto = ApplicationLogger.prototype;
for(let level of levels) {
  level = level.levelStr.toLowerCase();
  proto[level] = (function(level) {
    return function(key, message) {
      const logger = this.logger;
      logger.addContext('key', key);
      logger[level](message);
    };
  })(level);
}
application = new ApplicationLogger();

access = log4js.getLogger('access');

module.exports = {
  console,
  system,
  application,
  access
};

systemlogger.js

const logger = require('./logger').system;

module.exports = function(options) {
  return function(err, req, res, next) {
    logger.error(err.message);
    next(err);
  };
};