debuggy

Debugging utility tool for development

This utility is similar to the debug module but without being a singleton, that is, it doesn't enable the debug mode of other third-party modules, which is undesirable. By default, the DEBUG environment variable is checked and it can contain any value, e.g. DEBUG=true.

The default formatter prints the messages to the stdout but you're free to log them anywhere by configuring a custom formatter. It also allows subnamespaces similar to the bole module.

// app.js
var debuggy = require('debuggy');
var logger = debuggy.createLogger();
var debug = logger('boot')('http').debug;

debug('Booting up HTTPS server');

$ node app.js
$ DEBUG=true node app.js
2015-01-12T14:17:00.302+01:00 +0ms boot:http Booting up HTTPS server

Custom formatter and environment variable

var util = require('util');
var debuggy = require('./lib');

var logger = debuggy.createLogger({
  env: 'TEST',
  // This is the default formatter function, adapt it to your needs
  format: function (data) {
    console.log(this.isoDate(data.date) + ', ' +
        this.delay(data.delay) +
        (data.namespace ? ', ' + data.namespace : '') + ', ' +
        util.format.apply(null, data.arguments));
  }
});
var debug = logger('boot')('http').debug;

// If process.env.TEST is truthy is will print the message
debug('Booting up HTTPS server');

$ node app.js
$ DEBUG=true node app.js
$ TEST=true node app.js
2015-01-12T14:17:50.207+01:00, +0ms, boot:http, Booting up HTTPS server

module.createLogger([options]) : Function
Returns a new logger instance. This instance is a function that creates a namespace when called (the namespace is optional). This new namespace can also create new subnamespaces, and so on. Each "namespace-maker" function has a debug function to log the messages.

var logger = require('debuggy').createLogger();
var debug;

debug = logger.debug;
// debug('foo') <timestamp> <delay> 'foo'

debug = logger('a').debug;
// debug('foo') -> <timestamp> <delay> a 'foo'

debug = logger('a')('b').debug;
// debug('foo') -> <timestamp> <delay> a:b 'foo'

Options:

• env - String
  Name of the environment variable that's checked to print the messages or not. Default is DEBUG.

• format - Function
  Function that formats the messages. By default, it prints to the stdout. It receives one argument, data, an object with the raw data. It contains the following properties:

  • arguments - Array
    Array of arguments passed to logger.debug().
  • date - Date
    Date instance of the current timestamp.
  • delay - Number
    Milliseconds between logging calls.
  • namespace - String | undefined
    Name of the namespace.

  this points to an object with some formatting functions:

  • this.isoDate(date) : String
    Returns de ISO date as string including the timezone offset.
  • this.delay(ms) : String
    Returns a more readable string representation of the delay between logging calls.

logger.debug(...arguments) : undefined
Logs a message. The parameters are untouched and are available in the custom formatter function in the data.arguments property.