README

@miroculus/log

Simple logging library for Node.js intended to be used internally at Miroculus.

Installation

npm i @miroculus/log

Getting Started

By default, the library will log everything to the console, including the log level:

const log = require('@miroculus/log')

log.info('some message')
// [INFO] some message

Logging Levels

The library includes the following logging levels:

critical
error
warn
info
debug

And you can enable them using the function setLevel, that receives the logging level you which to enable, and will disable all the levels it has underneath.

e.g.:

// This will disable the `info` and `debug` logging levels.
log.setLevel('warn')

Scoped Logging

You can create an scoped logger, which will include the scope when logging it to the console. e.g.:

const { createLog } = require('@miroculus/log')

const log = createLog('my-library')

log.info('another message')
// [INFO][my-library] another message

Multiple scopes can also be used:

const { createLog } = require('@miroculus/log')

const log = createLog('my-library', 'sub-module')

log.info('another message')
// [INFO][my-library][sub-module] another message

Logging Triggers

If you want to execute some callback everytime a log is emitted, you can listen to the event log, e.g:

const log = require('@miroculus/log')

log.on('log', ({ level, scopes, args, time }) => {
  // level === 'error'
  // scopes === []
  // time === Date.now()
  const [err] = args
  // do wathever you like with the logged err object
})

log.error(new Error('some error'))

A more complex example can be found at examples/sentry.js which shows how to do a very simple implementation with Sentry.

Default console logger

By default, the logger will log everything to the console, but this functionality can be disabled by running the following on the base logger:

const log = require('@miroculus/log')

log.disableDefaultConsoleLogger()

// To re-enable the default listener:
log.enableDefaultConsoleLogger()

This is useful to be able to define a custom console logger using the Logging Triggers, or disable the console logger altogether.

Usage no npm install needed!