simple pretty log4j-like logging (requires chalk for color)

logging.js

var util = require('util');
var chalk = require('chalk');

var LOG_TYPE = chalk.bold.black('[') + '%s' + chalk.bold.black(']') + ':';
var ALL = {
  type: 'ALL'
};
var TRACE = {
  type: 'TRACE',
  fn: console.log,
  get prefix() {
    return util.format(LOG_TYPE, chalk.bold.white(this.type));
  },
};
var DEBUG = {
  type: 'DEBUG',
  fn: console.log,
  get prefix() {
    return util.format(LOG_TYPE, chalk.white(this.type));
  },
};
var INFO = {
  type: 'INFO',
  fn: console.info,
  get prefix() {
    return util.format(LOG_TYPE, chalk.bold.cyan(' ' + this.type));
  }
};
var WARN = {
  type: 'WARN',
  fn: console.warn,
  get prefix() {
    return util.format(LOG_TYPE, chalk.bold.yellow(' ' + this.type));
  }
};
var ERROR = {
  type: 'ERROR',
  fn: console.error,
  get prefix() {
    return util.format(LOG_TYPE, chalk.bold.red(this.type));
  }
};
var FATAL = {
  type: 'FATAL',
  fn: console.error,
  get prefix() {
    return util.format(LOG_TYPE, chalk.bold.white.bgRed(this.type));
  }
};
var OFF = {
  type: 'OFF'
};

var LEVELS = [
  ALL,
  TRACE,
  DEBUG,
  INFO,
  WARN,
  ERROR,
  FATAL,
  OFF
].reduce(indexByType, {});
var priority = ALL.priority;

function indexByType(map, value, index) {
  map[value.type] = value;
  value.priority = Math.pow(2, index);
  return map;
}

function log(level, args) {
  if (level.priority < priority || typeof level.fn !== 'function') {
    return;
  }
  args = [].slice.call(args);
  args.unshift(level.prefix);
  level.fn.apply(console, args);
}

function debug() {
  log(DEBUG, arguments);
}

function disable() {
  priority = OFF.priority;
}

function enable() {
  priority = ALL.priority;
}

function error() {
  log(ERROR, arguments);
}

function info() {
  log(INFO, arguments);
}

function warn() {
  log(WARN, arguments);
}

function setLevel(level) {
  if (level > 0 && ((level & (level - 1)) === 0)) {
    priority = level;
  } else {
    level = String(level).trim().toUpperCase();
    if (LEVELS[level]) {
      priority = LEVELS[level].priority;
    }
  }
}

module.exports = {
  debug: debug,
  disable: disable,
  enable: enable,
  error: error,
  info: info,
  setLevel: setLevel,
  warn: warn
};