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Logr

logr is a lightweight, but extensible, logging and debugging library for node.js. The main difference between logr and most of the other logging libraries is that you can pass in a module name and section name to easily view and filter your logs.

logr

Installation

Install via npm 

npm install logr

Basic Usage

app.js 

var lg = require('logr')('app');

lg.info('init');

model.js 

var lg = require('logr')('app', 'model');

lg.info('init');

output:

logr

Default Log Levels

levels: [
    'EMERGENCY',
    'CRITICAL',
    'ERROR',
    'WARN',
    'NOTICE',
    'INFO',
    'DEBUG'
]

Based on the log levels, you can call lg.notice or lg.warn, etc.

Adapters

Console

By default the console adapter is enabled, but if you want more control over the output you can do something like this: 

var lg = require('logr')('app', { console: false });

//this will use the console adapter for only INFO level logs
lg.use(lg.adapters.console({
    color: false,
    timestamp: false
}, 'INFO');

Future

Currently, only the console adapter is build into the core library, but more adapters are coming soon:

Advanced Usage

Options

In your root app file you can pass some options on to logr. Currently here are the options that you can pass when you first initialize logr 

var lg = require('logr')('app', {
    console: false, //disables console adapter (global for all instances)
    filter: ['app', 'module1'], //will only log those modules (global for all instances)
    levels: [ //can define custom levels (specific to this instance of lg)
        'TEST1',
        'TEST2'
    ]
});

Custom adapters

Creating a custom adapter is very easy. 

var lg = require('logr')('app');

lg.use(function(module, section, level, message, data){}, {level filter}, {module filter}, {section filter});

Here's an example: 

lg.use(function(module, section, level, message, data) {
    console.error('FIX THIS NOW: ' + message);
}, 'ERROR', 'app');

This will fire on all lg.error calls in the app module

logr

Filtering

Logr lets you apply module filters across all instances, so that you can easily debug specific modules. 

var lg = require('logr')('app');
lg.filter(['app', 'module1']);

Now only app and module1 log calls will passed on to your adapters. This is great for debugging a specific module without distraction from other log calls.

Filtering with enviornment variables

In addition to the filter call, you can also use enviornment vars like so: 

$ LOGR=app node app.js

This is the same as doing lg.filter('app') in your code.

Future

Authors