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  • License MIT

a neat logger for the command line

Package Exports

  • neat-log
  • neat-log/output

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (neat-log) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

neat-log

npm travis standard

A neat logger for command line tools, inspired by Choo! I've heard so much about how awesome front-end javascript has gotten, I wanted to bring some of that magic to command line applications. Used in the Dat command line tool.

  • Use tagged template literals to output to console log.
  • Automatically diff template output with existing console (via ansi-diff-stream) (pretty much React for your terminal).
  • Update console output in any order with event based output.
  • Pretty neat!

Example

Each neat logger has two components: a view and functions that modify state and emit events.

var neatLog = require('neat-log')
var output = require('neat-log/output')

var neat = neatLog(view)
neat.use(countTheSeconds)

function view (state) {
  // This gets printed to the console! Wow. So neat.
  return output`
    Hello World!
    I've been running for ${state.seconds} second${state.seconds === 1 ? '' : 's'}.
  `
}

function countTheSeconds (state, bus) {
  state.seconds = 0
  setInterval(function () {
    state.seconds++
    bus.emit('render')
  }, 1000)
  bus.emit('render')
}

This example will print to the console:

Hello world!
I've been running for 0 seconds.

And update every second!

More examples:

  • example folder
  • count-files - basic example with a single view and use function.
  • dat - full command line application with multiple views, components, etc.

Install

npm install neat-log

API

Heavily inspired by Choo! If you get confused here, check docs there because they are much nicer =).

var neat = neatLog(view(state), [opts])

  • views is a single function or array of functions that return string(s) to output to the console. views are passed the state as the first argument.
  • opts.logspeed (default 250ms) - throttles how often output is rendered.
  • opts.quiet - shhhh.... do not print anything
  • opts.debug - print the whole view every time render is called.

Both opts.quiet and opts.debug are handled in status-logger.

neat.use(callback(state, bus))

Use a function (state, bus) to change state and emit events via the bus. You can call bus.emit() to emit a new event and bus.on() to listen. Emitter is an instance of nanobus.

bus also has some special functions exposed:

bus.render()

Cause an immediate render (normally it'd be throttled). This is helpful to do before exiting.

bus.clear()

Clear all existing output. This is useful to do before throwing error messages:

bus.clear()
console.error('my error')
process.exit(1)

neat.render()

For an immediate render. Helpful outside of a use function.

neat.reset()

Reset the ansi-diff-stream instance. Can help fix broken lines or other weird printing output. Happens automatically on terminal resize.

var output = require('neat-log/output')

Get a tagger for your template literals to make them nicer. Removes spaces and stuff™.

TODO

  • Use bus.on('*') to make a cool debug option
  • Be smarter about when lines break to multiple lines.
  • Other neat things

License

MIT