A Logging framework for Node.js and Meteor
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README.md

Pince

Pince is a lightweight logger that combines some of the best properties of log4j and node. It's equally usable in Node, (most) browsers, and Meteor (client and server).

It was developed for MadEye.

Features:

  • Log levels: error, warn, info, debug, trace
  • Dynamically change the log level on the client.
  • Change the log level with no code changes on the server.
  • Logging is very lightweight when there's nothing listening to it.
  • Each logger has a name -- you can set levels individually by name!
  • Names can be hierarchically namespaced by separating them with ':'s, like myLibrary:aModule:thisObject.
  • Set log levels by any level of the namespace hierarcy!

Installation (Node.js)

To install, npm install pince.

In any file you wish to make a logger, require it via Logger = require('pince');

Installation (Meteor)

To install, just meteor add jag:pince. The global Logger symbol will be there waiting for you.

By default, on the server Meteor will prepend a string to logs that includes a timestamp (amongst other things). To silence Meteor's prefix, run meteor with the --raw-logs flag: meteor --raw-logs.

Installation (Browser)

Just source pince-browser.js.

Usage

Set the log level:

//Default is info
Logger.setLevel('trace');

Make a new logger:

var log = new Logger('router');
log.info("Routing.");
//2013-10-31 11:29:36.097 info:  [router]  Routing.
log.trace("Setting up routes...");
//2013-10-31 11:29:36.101 trace:  [router]  Setting up routes...

Set individual levels:

Logger.setLevel('info');
Logger.setLevel('controller', 'trace');
var routerLog = new Logger('router');
var controllerLog = new Logger('controller');

routerLog.trace("Can't hear me!");
//Nothing
controllerLog.trace("Can hear me.");
//2013-10-31 11:31:21.906 trace:  [controller]  Can hear me.

Logger.setLevels({router:'debug', controller:'warn'});
routerLog.info("Finally! Someone is listening to me.");
//2013-10-31 11:32:48.374 info:  [router]  Finally! Someone is listening to me.
controllerLog.info("Hello? Hello??");
//Nothing

Hierarchically name and set levels:

var routerLog = new Logger('myPackage:router');
var controllerLog = new Logger('myPackage:controller');
Logger.setLevel('myPackage', 'info');
Logger.setLevel('myPackage:controller', 'debug');

routerLog.info('You can see this.');
routerLog.debug('You cannot see this; myPackage level is set to info.');
controllerLog.debug('You can see this, myPackage:controller level is set to debug.');

Control the output formatting:

var log = new Logger('router');
log.info('A message.');
//2013-10-31 11:32:48.374 info:  [router]  A message.
Logger.setFormat('%N:%L [%T] %M');
log.info('A message.');
//router:info [2013-10-31 11:32:48.374] A message.
Logger.setDateFormat('YYYY_MM_DD_HH_mm_ss');
log.info('A message.');
//router:info [2013_10_31_11_32_48] A message.

To control the formatting, use Logger.setFormat(str) and Logger.setDateFormat(str). The former controls the overall format, and includes the escape characters:

  • %T The timestamp string (as controlled by setDateFormat()).
  • %L The logging level, eg info.
  • %N The name of the logger, eg myPackage:router.
  • %M The message to log.

In addition, you can control the appearance of the timestamp. The timestamp format string has the special sequences:

  • YYYY The full 4-digit date.
  • MM The 2-digit month (1-12).
  • DD The 2-digit date (1-31).
  • HH The 2-digit hour (00-23).
  • mm The 2-digit minute (00-59).
  • ss The 2-digit second (00-59).
  • SSS The 3-digit millisecond (000-999).