Logging config in JS

logging-app-utils.js

/**
 * utils.js
 */

import Radio from 'backbone.radio';

var CHANNEL = Radio.channel('quickpost-app');

var my_util_function = function() {
  var logger = CHANNEL.request('get_logger', 'utils');
  logger.info('An info message on the utils logger');
  logger.debug('A debug message on the utils logger');
  logger.warn('A warn message on the utils logger');
};

module.exports = {
  my_util_function: my_util_function
}

/**
 * app.js
 */

import log from 'loglevel';
import log_message_prefix from 'loglevel-message-prefix';

import Radio from 'backbone.radio';
import Mn from 'backbone.marionette';

var CHANNEL = Radio.channel('quickpost-app');

module.exports = Mn.Application.extend({
  logger_prefix: 'qp-',
  loggers: {
    app: { level: 'trace' },
    utils: { level: 'error' },
    router: { level: 'warn' },
    card_detail: { level: 'debug' },
    dashboard: { level: 'error' },
  },
  onStart: function() {
    this.create_loggers();
    this.logger = CHANNEL.request('get_logger', 'app');
    this.logger.info('A log message on the app logger');
  },
  create_loggers: function() {
    this._loggers = {};
    _.each(this.loggers, (options, logger_name) => {
      logger_name = `${this.logger_prefix}-${logger_name}`;
      var logger = log.getLogger(logger_name);
      if(options.level) {
        logger.setLevel(options.level);
      }

      /* Prefix log messages */
      log_message_prefix(logger, {
        prefixes: ['level'],
        staticPrefixes: [logger_name.toUpperCase()]
      });

      this._loggers[logger_name] = logger;
    });

    CHANNEL.reply('get_logger', (logger_name) => {
      var default_logger = this._loggers['qp-app'];
      default_logger.debug(`Getting logger ${logger_name}`);
      
      /* Remove the prefix if its on, and add it back so that this function can optionally accept the prefix */
      logger_name = logger_name.replace(new RegExp("/^(" + this.logger_prefix + "\.)/"),'');
      logger_name = this.logger_prefix + logger_name;
      
      /* Get the logger using the name and prefix as the key */
      var logger = this._loggers[logger_name];
      
      /* If the logger couldn't be found, fallback to the app logger */
      if(!logger) {
        logger = default_logger;
        logger.warn(`No logger found for ${logger_name}. Falling back to the default logger.`);
      }
      return logger;
    });
  },

});