megasniff: Debugging promise-chains for humans

Megasniff

Better debugging for chained functions (promises, streams, etc.). Inspired by supersniff , but with these improvements in mind:

• Support for custom loggers (like bunyan , winston , or other services)
• No forced tag
• Using error levels for errors

Things to do:

• Custom configureable log levels
• Decorator functions (e.g. error => error.message )

Motivation

Can be found here . It shall be a readable replacement for:

getData()
  .then(data => {
    console.info(data)
    return data
  })
  .then(transformData)

Installation

npm install megasniff

Examples

const megasniff = require('megasniff')

const reveersedList = new Promise(resolve => resolve([3, 1, 2]))
  .then(megasniff)
  .then(list => list.sort())
  .then(megasniff)
  .then(list => list.reverse())
  .then(megasniff)

This yields in the console:

[ 3, 1, 2 ]
[ 1, 2, 3 ]
[ 3, 2, 1 ]

const megasniff = require('megasniff')

new Promise(resolve => resolve('Good'))
  .then(megasniff.config({ suffix: `Value at ${new Date()}:` }))

This yields on stdout:

Good Value at Wed Oct 17 2018 15:47:26 GMT+0200 (Central European Summer Time)

const megasniff = require('megasniff')
const logger = console

new Promise((resolve, reject) => reject(new Error('Bad')))
  .catch(megasniff.config({ suffix: '.. We are doomed' }))
  .catch(error => error)

This yields on stderr:

Error: Bad ... We are doomed

API

Default Usage:

const megasniff = require('megasniff')

const sortedList = new Promise(resolve => resolve([3, 1, 2]))
  .then(megasniff)
  .then(list => list.sort())
  .then(megasniff)

megasniff is a function that logs and returns the passed value. The value is logged either to stdout or sterr depending on the passed value.

Configuration:

const megasniff = require('megasniff')
const logger = console
new Promise(resolve => resolve('Good Software'))
  .then(megasniff.config({ prefix: `[megasniff]`, logger }))

megasniff.config takes an object as argument. Megasniff can be configured with these optional parameters:

key value log External logger logger Other key for external logger prefix Will be prefixed the logged value suffix Will be suffixed the logged value