Signale

👋 Hackable console logger

Description

Hackable and configurable to the core, signale can be used for logging purposes, status reporting, as well as for handling the output rendering process of other node modules and applications.

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Highlights

• 16 out-of-the-box loggers
• Hackable to the core
• Clean and beautiful output
• Integrated timers
• Custom pluggable loggers
• Interactive and regular modes
• Secrets & sensitive information filtering
• Filename, date and timestamp support
• Scoped loggers and timers
• Scaled logging levels mechanism
• String interpolation support
• Multiple configurable writable streams
• Simple and minimal syntax
• Globally configurable through package.json
• Overridable configuration per file and logger

Contents

• Description
• Highlights
• Install
• Usage
• Configuration
• API
• Development
• Related
• Who's Using It?
• Team
• License

Install

npm install signale

Usage

Default Loggers

Import signale and start using any of the default loggers.

View all of the available loggers.

• await
• complete
• error
• debug
• fatal
• fav
• info
• note
• pause
• pending
• star
• start
• success
• wait
• warn
• watch
• log

const signale = require('signale');

signale.success('Operation successful');
signale.debug('Hello', 'from', 'L59');
signale.pending('Write release notes for %s', '1.2.0');
signale.fatal(new Error('Unable to acquire lock'));
signale.watch('Recursively watching build directory...');
signale.complete({prefix: '[task]', message: 'Fix issue #59', suffix: '(@klauscfhq)'});

Custom Loggers

To create a custom logger define an options object yielding a types field with the logger data and pass it as argument to a new signale instance.

const {Signale} = require('signale');

const options = {
  disabled: false,
  interactive: false,
  logLevel: 'info',
  scope: 'custom',
  secrets: [],
  stream: process.stdout,
  types: {
    remind: {
      badge: '**',
      color: 'yellow',
      label: 'reminder',
      logLevel: 'info'
    },
    santa: {
      badge: '🎅',
      color: 'red',
      label: 'santa',
      logLevel: 'info'
    }
  }
};

const custom = new Signale(options);
custom.remind('Improve documentation.');
custom.santa('Hoho! You have an unused variable on L45.');

Here is an example where we override the default error and success loggers.

const {Signale} = require('signale');

const options = {
  types: {
    error: {
      badge: '!!',
      label: 'fatal error'
    },
    success: {
      badge: '++',
      label: 'huge success'
    }
  }
};

const signale = new Signale();
signale.error('Default Error Log');
signale.success('Default Success Log');

const custom = new Signale(options);
custom.error('Custom Error Log');
custom.success('Custom Success Log');

The options object can hold any of the following attributes: disabled, interactive, stream, scope and types.

disabled

• Type: Boolean
• Default: false

Disables the logging functionality of all loggers belonging to the created instance.

interactive

• Type: Boolean
• Default: false

Switches all loggers belonging to the created instance into the interactive mode.

logLevel

• Type: String
• Default: 'info'

Sets the general logging level of the created instance. Can be 'info' - logs all messages of all loggers, 'timer' - logs only messages of time, timeEnd, debug, warn, error & fatal loggers, 'debug' - logs only messages of debug, warn, error & fatal loggers, 'warn' - logs only messages of warn, error & fatal loggers & 'error' - logs only messages of error & fatal loggers.

secrets

• Type: (String|Number)[]
• Default: []

An array holding secrets/sensitive-information to be removed from the body and metadata of to-be-logged messages and replaced with the default '[secure]' string.

stream

• Type: stream.Writable|stream.Writable[]
• Default: process.stdout

Destination to which the data is written, can be a single valid Writable stream or an array holding multiple valid Writable streams.

scope

• Type: String|String[]

Name of the scope the logger is reporting from.

types

• Type: Object

Holds the configuration of the custom and default loggers.

Additionally, the configuration object of each custom/default logger type, defined in the types option, can hold any of the following attributes: badge, label, color and logLevel.

badge

• Type: String

The icon corresponding to the logger.

label

• Type: String

The label used to identify the type of the logger.

color

• Type: String

The color of the label, can be any of the foreground colors supported by chalk.

logLevel

• Type: String
• Default: 'info'

The log level corresponding to the logger. Messages originating from the logger are displayed only if the log level is greater or equal to the above described general logging level logLevel of the Signale instance.

Scoped Loggers

To create a scoped logger from scratch, define the scope field inside the options object and pass it as argument to a new signale instance.

const {Signale} = require('signale');

const options = {
  scope: 'global scope'
};

const global = new Signale(options);
global.success('Successful Operation');

To create a scoped logger based on an already existing one, use the scope() function, which will return a new signale instance, inheriting all custom loggers, timers, streams, configuration, interactive mode & disabled statuses from the initial one.

const signale = require('signale');

const global = signale.scope('global scope');
global.success('Hello from the global scope');

function foo() {
  const outer = global.scope('outer', 'scope');
  outer.success('Hello from the outer scope');

  setTimeout(() => {
    const inner = outer.scope('inner', 'scope'); 
    inner.success('Hello from the inner scope');
  }, 500);
}

foo();

Interactive Loggers

To initialize an interactive logger, create a new signale instance with the interactive attribute set to true. While into the interactive mode, previously logged messages originating from an interactive logger, will be overridden only by new ones originating from the same or a different interactive logger. Note that regular messages originating from regular loggers are not overridden by the interactive ones.

const {Signale} = require('signale');

const interactive = new Signale({interactive: true, scope: 'interactive'});

interactive.await('[%d/4] - Process A', 1);

setTimeout(() => {
  interactive.success('[%d/4] - Process A', 2);
  setTimeout(() => {
    interactive.await('[%d/4] - Process B', 3);
    setTimeout(() => {
      interactive.error('[%d/4] - Process B', 4);
      setTimeout(() => {}, 1000);
    }, 1000);
  }, 1000);
}, 1000);

Writable Streams

By default, all signale instances log their messages to the process.stdout stream. This can be modified, to match your own preference, through the stream property, where you can define a single or multiple valid Writable streams, which will be used by all logger types to log your data. Additionally, it is possible to define one or more Writable streams exclusively for a specific logger type, thus write data independently from the rest logger types.

const {Signale} = require('signale');

const options = {
  stream: process.stderr, // All loggers will now write to `process.stderr`
  types: {
    error: {
      // Only `error` will write to both `process.stdout` & `process.stderr`
      stream: [process.stdout, process.stderr]
    }
  }
};

const signale = new Signale(options);
signale.success('Message will appear on `process.stderr`');
signale.error('Message will appear on both `process.stdout` & `process.stderr`');

Secrets Filtering

By utilizing the secrets option, secrets and other sensitive information can be filtered out from the body as well as the metadata, i.e. scope names etc, of to-be-logged messages. The option is part of the configuration object passed to a Signale instance on its initialization, and is of type Array<String|Number>. The array can hold multiple secrets, all of which are removed, if present, from the to-be-logged messages and are replaced with the default '[secure]' string. Additionally, when the unary signale.scope(name) function is used, the returned Signale instance inherits all the secrets belonging to its parent. The secrets checking process is performed in a case-sensitive manner. Also, the unary signale.addSecrets() and the nullary signale.clearSecrets() functions are available through the API for adding and clearing secrets respectively.

It is critical and highly recommended to not type directly secrets in your code, thus the following example serves only as a simple & easily reproducible usage demonstration.

const {Signale} = require('signale');

// In reality secrets could be securely fetched/decrypted through a dedicated API 
const [USERNAME, TOKEN] = ['klaussinani', 'token'];

const logger1 = new Signale({
  secrets: [USERNAME, TOKEN]
});

logger1.log('$ exporting USERNAME=%s', USERNAME);
logger1.log('$ exporting TOKEN=%s', TOKEN);

// `logger2` inherits all secrets from its parent `logger1`
const logger2 = logger1.scope('parent');

logger2.log('$ exporting USERNAME=%s', USERNAME);
logger2.log('$ exporting TOKEN=%s', TOKEN);

Timers

Timer are managed by the time() and timeEnd() functions. A unique label can be used to identify a timer on initialization, though if none is provided the timer will be assigned one automatically. In addition, calling the timeEnd() function without a specified label will have as effect the termination of the most recently initialized timer, that was created without providing a label.

const signale = require('signale');

signale.time('test');
signale.time();
signale.time();

setTimeout(() => {
  signale.timeEnd();
  signale.timeEnd();
  signale.timeEnd('test');
}, 500);

Configuration

Global

To enable global configuration define the options under the signale namespace in your package.json.

The following illustrates all the available options with their respective default values.

{
  "signale": {
    "displayScope": true,
    "displayBadge": true,
    "displayDate": false,
    "displayFilename": false,
    "displayLabel": true,
    "displayTimestamp": false,
    "underlineLabel": true,
    "underlineMessage": false,
    "underlinePrefix": false,
    "underlineSuffix": false,
    "uppercaseLabel": false
  }
}

View all of the available options in detail.

displayScope

• Type: Boolean
• Default: true

Display the scope name of the logger.

displayBadge

• Type: Boolean
• Default: true

Display the badge of the logger.

displayDate

• Type: Boolean
• Default: false

Display the current local date in YYYY-MM-DD format.

displayFilename

• Type: Boolean
• Default: false

Display the name of the file that the logger is reporting from.

displayLabel

• Type: Boolean
• Default: true

Display the label of the logger.

displayTimestamp

• Type: Boolean
• Default: false

Display the current local time in HH:MM:SS format.

underlineLabel

• Type: Boolean
• Default: true

Underline the logger label.

underlineMessage

• Type: Boolean
• Default: false

Underline the logger message.

underlinePrefix

• Type: `B