log-2000

log-2000 is the result of an attempt at creating a highly customizable logger with an interface that is easy to extend.

Installation

npm install --save log-2000

Usage

var Log = require('log-2000')

var log = Log()

log.info('Hello.')

Will print

{ level: 'info',
  date: Fri Jan 29 2016 09:25:10 GMT+0100 (W. Europe Standard Time),
  message: 'Hello.' }

Examples

Examples can be found here. Play with them on tonicdev.com/npm/log-2000 or locally by doing:

git clone https://github.com/mickvangelderen/log-2000.git
cd log-2000/examples
npm install
node basic

Customizing log-2000

With log-2000, you can customize log levels, what is being logged and where it is being logged.

The default configuration of log-2000 can be viewed in log-factory.

Customizing levels

The levels can be customized like this:

var Log = require('log-2000')

var log = Log({
  levels: [ 'my', 'own', 'levels' ]
})

log.my('hello!')

Customizing writers

These are the writers log-2000 provides:

• console-writer

var Log = require('log-2000')
var consoleWriter = require('log-2000/lib/console-writer')

var log = Log({
  writers: [ consoleWriter ]
})

Customizing transformers

These are the transformers log-2000 provides:

• attach-date
• attach-level
• coerce-string-to-object
• coerce-anything-to-object
• json-serializer

var Log = require('log-2000')
var attachDate = require('log-2000/lib/attach-date')

var log = Log({
  transformers: [ attachDate ]
})

Extending log-2000

Nowadays, extensibility is important because there are so many talented and ingenious people out there and node is being used for an increasing variety of tasks.

Creating writers

A writer is simply a function that accepts a level and data parameter. The function myWriter in the following code for example is a writer.

function myWriter(level, data) {
  console.log(level, data)  
}

For more interesting writers I recommend using the factory pattern. Check the default console writer for an example.

It would be nice if all writer factories accepted a transformers option that transforms incoming data like this:

data = transformers.reduce((d, f) => f(level, d), data)

This ensures that a user can transform the data exactly how they want for each writer. For example one might want to log human readable messages to the console and JSON lines to a file.

Creating transformers

A transformer is simply a function that accepts a level and data parameter and returns a new data object. The following code for example is a transformer.

function myTransformer(level, data) {
  return Object.assign({ level: level }, data)
}