Logger library

logger-js is a npm logger library for NodeJS

This logger is primarly designed for a backend usage, to handle the logs of a node server, or for a bot. It's lighter and easier to use than other libraries and does not require any configuration (at least for a small/medium project). It's particulary fast and require almost no running time.

The logger will write the logs by default in the logs/ directory to the root of your project. You can change the location and the name of this folder. The default log file is logs.log.

This project is part of the vener.fr project, to collect the errors and different information of the server (express).

Installation

To install the package, just run :

npm install --save @dorianb/logger-js

Then in the .js file :

const Logger = require('@dorianb/logger-js')

Logger.info('Server is starting on port 9000')
Logger.debug('172 clients are currently connected')
Logger.warn('Unsafe call from client @7655671')
Logger.error('Socket &[email protected] doesn\'t exist')
Logger.fatal('Internet connection lost')

Documentation

Classes

Logger

Typedefs

LevelsObject : Object

A dictionary of the logger levels indexed by priority

OptionsObject : Object

Logger

• Logger
  • .options ⇒ OptionsObject
  • .version ⇒ string
  • .levels ⇒ LevelsObject
  • .setOptions(opts)
  • .log(filename, level, message) ↩︎
  • .info(info, [filename]) ↩︎
  • .debug(debug, [filename]) ↩︎
  • .warn(warning, [filename]) ↩︎
  • .error(error, [filename], [opts]) ↩︎
  • .fatal(error, [filename]) ↩︎
  • .clear([...filename]) ↩︎
  • .getLevel(level) ⇒ array
  • .addLevel(newLevel) ⇒ array
  • .on(event, callback)

Logger.options ⇒ OptionsObject

Getter: Return the options of the logger
Example

const loggerOptions = Logger.options

Logger.version ⇒ string

Returns: string - the version number of the logger
Getter: Version getter
Example

const version = Logger.version

Logger.levels ⇒ LevelsObject

Getter: Levels object getter - All the levels of the logger
Example

const levels = Logger.levels

Logger.setOptions(opts)

Param	Type	Description
opts	OptionsObject	logger default values

Example

Logger.setOptions({filename: 'production.log'})

Logger.log(filename, level, message) ↩︎

Chainable

Param	Type	Description
filename	string	file where the log is written
level	number | string	level of the log
message	string	content of the log

Example

Logger.log('network.log', 'WARN', 'Socket disconnected')
Logger.log('network.log', 2, 'Socket disconnected')
// --> [10-06-2020 06:43:51] - WARN - Socket disconnected

Logger.info(info, [filename]) ↩︎

Chainable

Param	Type	Default	Description
info	string		content of the log
[filename]	string	"options.filename"	filename without path

Example

Logger.info('Server has started')
Logger.info('Server has started', 'server.log')

Logger.debug(debug, [filename]) ↩︎

Chainable

Param	Type	Default	Description
debug	string		content of the log
[filename]	string	"options.filename"	filename without path

Example

Logger.debug(`Client ID = ${clientID}`)
Logger.debug(`Client ID = ${clientID}`, 'clients.log')

Logger.warn(warning, [filename]) ↩︎

Chainable

Param	Type	Default	Description
warning	string		content of the log
[filename]	string	"options.filename"	filename without path

Example

Logger.warn(`Database disconnected`)
Logger.warn(`Database disconnected`, 'connections.log')

Logger.error(error, [filename], [opts]) ↩︎

Chainable

Param	Type	Default	Description
error	string		content of the log
[filename]	string	"options.filename"	filename without path
[opts]	object	{}	options

Example

Logger.error(`Connection to 127.0.0.1:2000 refused`)
Logger.error(`Connection to 127.0.0.1:2000 refused`, 'logs.log')

Logger.fatal(error, [filename]) ↩︎

Chainable

Param	Type	Default	Description
error	string		content of the log
[filename]	string	"options.filename"	filename without path

Example

Logger.fatal(`Division by zero`)
Logger.fatal(`Division by zero`, 'big_errors.log')

Logger.clear([...filename]) ↩︎

Chainable

Param	Type	Default	Description
[...filename]	string	"options.filename"	The filenames of the files to clear or 'all' if all the files should be cleaned

Example

Logger.clear() // clear the default file (options.filename)
Logger.clear('client.log')
Logger.clear('client.log', 'connections.log', 'logs.log')
Logger.clear('all')

Logger.getLevel(level) ⇒ array

Returns: array - [index, label]

Param	Type	Description
level	string | number	the index or the label of the level

Example

const testLevel = Logger.getLevel('warn') // --> ["2", "WARN"]
const testLevel = Logger.getLevel(2)      // --> ["2", "WARN"]

Logger.addLevel(newLevel) ⇒ array

Returns: array - the level array : [index, label]

Param	Type	Description
newLevel	string	The label of the new level

Example

const [importantLevel, importantLabel] = Logger.addLevel('Important')
Logger.log('logs.log', importantLevel, 'Important message which will be display on top of all other levels')

Logger.on(event, callback)

Param	Type	Description
event	string	'log'
callback	function

Example

Logger.on('log', log => console.log(log))
Logger.on('error', handleErrorsFunction)

LevelsObject : Object

A dictionary of the logger levels indexed by priority

Example

levels = {
     0: 'INFO',
     1: 'DEBUG',
     2: 'WARNING',
     3: 'ERROR',
     4: 'FATAL'
 }

OptionsObject : Object

Properties

Name	Type	Default	Description
[filename]	string	"'logs.log'"	The name of the default log file
[folder]	string	"'./logs/'"	The folder where logs files will be located (sorry for the name, couldn't find more descriptive)
[extension]	string	"'.log'"	The extension to use for logs files
[useMoment]	boolean	false	Use moment-js to format the dates. Allow timezone options but has a performance cost
[timezone]	string	"'Europe/Berlin'"	The moment timezone for the date
[console_logs]	boolean	false	Use console.log to displays logs instead of writing it in a log file
[displayLevel]	string | number	0	The level below a log is not displayed
[showPID]	boolean	false	Display the PID of the process in the log
[showHostname]	boolean	false	Display the hostname in the log
[align]	string	"left"	Where should the level be aligned ('left'

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2020 © Dorian Beauchesne