Elecpen NPM | npm.io

ElecPen

We take logger as a function to receive a record and output to a stream, and elecPen is a simple logger creator.

API

elecPen(writable, prefix, dateFormat)

Param	Description
writables	One or an array of writable stream for logging
prefix	The prefix of the record
dateFormat	Date format for logger or pass `true` to use the default format

Default logger

A set of logger is provided by a default logger creator which provide some useful logger like info or error.

Options

Option	Type	Description
infoFile	string, function	File name for logging info and verbose
errFile	string, function	File name for logging error and warning
timestamp	string, boolean	Date format for logger or pass `true` to use the default format
append	boolean	If file exists, append new entries to it instead of truncating
logToConsole	boolean	Output the message to console, it will be default to true in dev mode

Methods

logger.verbose
logger.info
logger.warning
logger.error

Example

You can you a set of default logger:

// use default logger
const opts = {
  infoFile: 'info.log',  // record info and verbose
  errFile: 'err.log', // record error and warning
  timestamp: true,
  append: true // default to true
}
const http = requrie('http')
const logger = require('elecpen').defaultLogger(opts)

http.createServer((req, res) => {
  logger.info('Recieve a request. Path: %s', req.path)
  res.end('Hello world.')
})
.listen(4000, _ => {
  logger.info('Server listening...')
})

Dynamic file name is supported, and it is useful to record log by separated file.

const opts = {
  infoFile () {
    const now = new Date()
    return `log-${now.getFullYear()}-${now.getMonth() + 1}`
  },
  errFile: 'err.log'
}
const logger = require('elecpen').defaultLogger(opts)
logger.info('Hello World!')

Or create you own logger:

const fs = require('fs')
const elecpen = require('elecpen')
const recorder = elecpen.streamRecorder()

const log = function (msg) {
  // dynamic stream
  const stream = recorder(
    _ => `log-${Date.now()}.log`,
    name => fs.createWriteStream(name, { flags: 'a' })
  )
  stream && elecpen(stream, 'Message', timestamp)(msg)
}
log('Hello World!')