Yurnalist

An elegant console reporter, borrowed from Yarn.

Introduction

Pretty console output makes developers happy and Yarn is doing a nice job. Yurnalist takes the internal console reporter code from Yarn and makes it available for use in other Node.js applications.

The current version is based on code from Yarn v1.13.0.

Yurnalist can be used to report many different things besides simple messages.

Features

log, info, warn, succes, error & command messages
progress bars
activity spinners
process steps
object inspection
lists
emojis
trees
tables
user question
user select
program header & footer

Install

yarn add yurnalist

Or if your prefer NPM

npm install yurnalist

How to use

Here is an example showing a combination of different reporter API functions.

import report from 'yurnalist'

/* A function to fake some async task */
function waitNumberOfSecs(secs) {
  return new Promise((resolve) => setTimeout(resolve, secs * 1000));
}

async function fetchSomething() {
  report.info('Please wait while I fetch something for you.');
  report.warn('It might take a little while though.');

  const spinner = report.activity();
  spinner.tick('I am on it!');

  try {
    await waitNumberOfSecs(1);
    spinner.tick('Still busy...');
    await waitNumberOfSecs(1);
    spinner.tick('Almost there...');
    await waitNumberOfSecs(1);
    report.success('Done!');
  } catch (err) {
    report.error(err);
  }

  spinner.end();
}

fetchSomething();

Requirements

Node >= 4

Examples

Examples showing different API functions are found in /examples. You can run them directly with node >= 7.6 (because of async/await syntax). For older versions you could use the --harmony flag, or otherwise Babel.

To run the activity example:

node examples/activity.js

Configuration

A normal import gives you a reporter instance configured with defaults for easy use. If you want something else you can call createReporter(options) to give you an instance with different options.

Options

These are the options of the reporter as defined by Flow:

type ReporterOptions = {
  verbose?: boolean,
  stdout?: Stdout,
  stderr?: Stdout,
  stdin?: Stdin,
  emoji?: boolean,
  noProgress?: boolean,
  silent?: boolean,
  nonInteractive?: boolean,
  peekMemoryCounter?: boolean
};

The defaults used are:

const defaults = {
  verbose: false,
  stdout: process.stdout,
  stderr: process.stderr,
  stdin: process.stdin,
  emoji: true,
  noProgress: false,
  silent: false,
  nonInteractive: false,
  peekMemoryCounter: false
}

The peekMemoryCounter is disabled by default. If you enable it, you'll have to call reporter.close() to stop its running timer. Otherwise your program will not exit. The memory counter can be used to display in the footer data.

Silent Mode and CI

Silent mode can be set via the options passed to createReporter. It disables output for various functions like info, list, activity and progress. The output from warning and error messages is not silenced.

Silent mode can also be enabled with the YURNALIST_SILENT environment variable.

In CI environments the output from activity and progress is disabled.

API

The API still needs some documentation, but most methods are straightforward. In the meantime you can also look at the examples and possibly even the tests.

The following functions are available:

table

step

inspect( thing: mixed )

Pretty-prints the thing.

list(title: string, items: Array, hints?: Object)

Generates a list of the provided items. Turns into a definition list if hints are provided.

Example of a simple list:

report.list('My grocery list', ['bananas', 'tulips', 'eggs', 'bamischijf']);

Outputs:

list My grocery list
   - bananas
   - tulips
   - eggs
   - bamischijf

Example with hints:

const items = ['bananas', 'tulips', 'eggs', 'bamischijf'];

const hints = {
  bananas: 'for baking',
  tulips: 'because it makes you happy',
  eggs: 'not the cheap ones though',
  bamischijf: 'if they have it',
};

report.list('My grocery list', items, hints);

Outputs:

list My grocery list
    - bananas
      for baking
   - tulips
      because it makes you happy
   - eggs
      not the cheap ones though
   - bamischijf
      if they have it

header

footer

log

success

error

info

command

warn

question

tree

activitySet

activity

select

progress

close

createReporter

Language

Yarn uses a language file for certain messages. For example if you try to skip a required question, or when you pick an invalid item from a select. This language file is not yet exposed in the Yurnalist API. The only supported language is English, as it is in Yarn at the moment.

I plan to make this configurable so that you can define your own messages in your own language .

Emojis

You can use Emojis in your output. Yurnalist should disable them if they are not allowed in the application environment.

Check:

Credits

Of course ❤️ and credits to all the contributers of Yarn. The ease with which I was able to extract this module from their codebase is proving some awesome engineering skills.

0x80 / yurnalist