Signale

^{Sponsored by:}

^{Spot, Resolve, and Prevent Downtime.}

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.

Read this document in: 简体中文.

You can now support the development process through GitHub Sponsors.

Visit the contributing guidelines to learn more on how to translate this document into more languages.

Come over to Gitter or Twitter to share your thoughts on the project.

• 19 out-of-the-box loggers
• Hackable to the core
• Clean and beautiful output
• Integrated timers
• Custom pluggable loggers
• TypeScript support
• 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

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

yarn add signale

npm install signale

Import signale and start using any of the default loggers.

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)'});

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, logLevel, secrets, stream, scope and types.

• Type: Boolean
• Default: false

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

• Type: Boolean
• Default: false

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

• Type: String
• Default: 'info'

Sets the general logging level of the created instance. Can be one of the following:

• 'info' - Displays all messages from all loggers.
• 'timer' - Displays messages only from the time, timeEnd, debug, warn, error & fatal loggers.
• 'debug' - Displays messages only from the debug, warn, error & fatal loggers.
• 'warn' - Displays messages only from the warn, error & fatal loggers.
• 'error' - Displays messages only from the error & fatal loggers.

• 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.

• 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.

• Type: String|String[]

Name of the scope the logger is reporting from.

• 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, logLevel & stream.

• Type: String

The icon corresponding to the logger.

• Type: String

The label used to identify the type of the logger.

• Type: String

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

• 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.

• 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.

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, secrets, streams, configuration, log level, 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();

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);

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`');

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);

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);

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
  }
}

To enable local configuration call the config() function on your signale instance. Local configurations will always override any pre-existing configuration inherited from package.json.

In the following example, loggers in the foo.js file will run under their own configuration, overriding the package.json one.

// foo.js
const signale = require('signale');

// Overrides any existing `package.json` config
signale.config({
  displayFilename: true,
  displayTimestamp: true,
  displayDate: false
}); 

signale.success('Hello from the Global scope');

Also, scoped loggers can have their own independent configuration, overriding the one inherited by the parent instance or package.json.

// foo.js
const signale = require('signale');

signale.config({
  displayFilename: true,
  displayTimestamp: true,
  displayDate: false
});

signale.success('Hello from the Global scope');

function foo() {
  // `fooLogger` inherits the config of `signale`
  const fooLogger = signale.scope('foo scope');

  // Overrides both `signale` and `package.json` configs
  fooLogger.config({
    displayFilename: true,
    displayTimestamp: false,
    displayDate: true
  });

  fooLogger.success('Hello from the Local scope');
}

foo();

• Type: Function

Can be any default or custom logger.

• Type: String

Can be one or more comma delimited strings.

const signale = require('signale');

signale.success('Successful operation');
//=> ✔  success  Successful operation

signale.success('Successful', 'operation');
//=> ✔  success  Successful operation

signale.success('Successful %s', 'operation');
//=> ✔  success  Successful operation

• Type: Error Object

Can be any error object.

const signale = require('signale');

signale.error(new Error('Unsuccessful operation'));
//=> ✖  error  Error: Unsuccessful operation
//        at Module._compile (module.js:660:30)
//        at Object.Module._extensions..js (module.js:671:10)
//        ...

• Type: Object

Can be an object holding the prefix, message and suffix attributes, with prefix and suffix always prepended and appended respectively to the logged message.

const signale = require('signale');

signale.complete({prefix: '[task]', message: 'Fix issue #59', suffix: '(@klaussinani)'});
//=> [task] ☒  complete  Fix issue #59 (@klaussinani)

signale.complete({prefix: '[task]', message: ['Fix issue #%d', 59], suffix: '(@klaussinani)'});
//=> [task] ☒  complete  Fix issue #59 (@klaussinani)

Defines the scope name of the logger.

• Type: String

Can be one or more comma delimited strings.

const signale = require('signale');

const foo = signale.scope('foo'); 
const fooBar = signale.scope('foo', 'bar');

foo.success('foo');
//=> [foo] › ✔  success  foo

fooBar.success('foo bar');
//=> [foo] [bar] › ✔  success  foo bar

Clears the scope name of the logger.

const signale = require('signale');

const foo = signale.scope('foo'); 

foo.success('foo');
//=> [foo] › ✔  success  foo

foo.unscope();

foo.success('foo');
//=> ✔  success  foo

Sets the configuration of an instance overriding any existing global or local configuration.

• Type: Object

Can hold any of the documented options.

// foo.js
const signale = require('signale');

signale.config({
  displayFilename: true,
  displayTimestamp: true,
  displayDate: true
});

signale.success('Successful operations');
//=> [2018-5-15] [11:12:38] [foo.js] › ✔  success  Successful operations

• Return Type: String

Sets a timers and accepts an optional label. If none provided the timer will receive a unique label automatically.

Returns a string corresponding to the timer label.

• Type: String

Label corresponding to the timer. Each timer must have its own unique label.

const signale = require('signale');

signale.time();
//=> ▶  timer_0  Initialized timer...

signale.time();
//=> ▶  timer_1  Initialized timer...

signale.time('label');
//=> ▶  label    Initialized timer...

• Return Type: Object

Deactivates the timer to which the given label corresponds. If no label is provided the most recent timer, that was created without providing a label, will be deactivated.

Returns an object {label, span} holding the timer label and the total running time.

• Type: String

Label corresponding to the timer, each timer has its own unique label.

const signale = require('signale');

signale.time();
//=> ▶  timer_0  Initialized timer...

signale.time();
//=> ▶  timer_1  Initialized timer...

signale.time('label');
//=> ▶  label    Initialized timer...

signale.timeEnd();
//=> ◼  timer_1  Timer run for: 2ms

signale.timeEnd();
//=> ◼  timer_0  Timer run for: 2ms

signale.timeEnd('label');
//=> ◼  label    Timer run for: 2ms

Disables the logging functionality of all loggers belonging to a specific instance.

const signale = require('signale');

signale.success('foo');
//=> ✔  success  foo

signale.disable();

signale.success('foo');
//=>

Enables the logging functionality of all loggers belonging to a specific instance.

const signale = require('signale');

signale.disable();

signale.success('foo');
//=>

signale.enable();

signale.success('foo');
//=> ✔  success  foo

Checks whether the logging functionality of a specific instance is enabled.

const signale = require('signale');

signale.success('foo');
//=> ✔  success  foo

signale.isEnabled();
// => true

signale.disable();

signale.success('foo');
//=>

signale.isEnabled();
// => false

Adds new secrets/sensitive-information to the targeted Signale instance.

• Type: (String|Number)[]

Array holding the secrets/sensitive-information to be filtered out.

const signale = require('signale');

signale.log('$ exporting USERNAME=%s', 'klaussinani');
//=> $ exporting USERNAME=klaussinani

signale.addSecrets(['klaussinani']);

signale.log('$ exporting USERNAME=%s', 'klaussinani');
//=> $ exporting USERNAME=[secure]

Removes all secrets/sensitive-information from the targeted Signale instance.

const signale = require('signale');

signale.addSecrets(['klaussinani']);

signale.log('$ exporting USERNAME=%s', 'klaussinani');
//=> $ exporting USERNAME=[secure]

signale.clearSecrets();

signale.log('$ exporting USERNAME=%s', 'klaussinani');
//=> $ exporting USERNAME=klaussinani

For more info on how to contribute to the project, please read the contributing guidelines.

• Fork the repository and clone it to your machine
• Navigate to your local fork: cd signale
• Install the project dependencies: npm install or yarn install
• Lint code for errors: npm test or yarn test

• qoa - Minimal interactive command-line prompts
• taskbook - Tasks, boards & notes for the command-line habitat
• hyperocean - Deep oceanic blue Hyper terminal theme

• Boostnote
• Docz
• Remix by Ethereum
• Semantic Release
• Shower
• Taskbook
• Vant

View in detail all the packages and repositories that are using Signale here.

• Klaudio Sinani (@klaudiosinani)
• Mario Sinani (@mariosinani)

A big thank you to all the people and companies supporting our Open Source work:

• Better Stack: Spot, Resolve, and Prevent Downtime.

MIT