@evokegroup/logger

Console logging based on severity.

Class: Logger

constructor(severity, { output, retain, onLog })

| Parameter | Type | Default | Description | | --------- | ---- | ------- | ----------- | | severity | Logger.Severity, number, string | Logger.Severity.Disabled | The maximum severity to output | | output | boolean | true | Output the messages to the console | | retain | Logger.Severity, number, string | Logger.Severity.Disabled | Message severity level to retain for later retrieval via getLogs() | | onLog | function | | A function to call whenever a message is logged regardless of severity |

Example

const Logger = require('@evokegroup/logger');
function doSomethingWithLogs(log) {
  // All logged messages are passed to this function as they are logged.
  // example: log = {
  //   severity: 2,
  //   logged: true,
  //   date: '2021-02-07T16:43:32.233Z',
  //   messages: [
  //     'Doing something'
  //   ]
  // }
}
const logger = new Logger(Logger.Severity.Info, { output: true, retain: Logger.Severity.Error, onLog: doSomethingWithLogs});
logger.info('Doing something'); // logged to console
logger.debug('Data', { firstName: 'John', lastName: 'Doe' }); // not logged to console
logger.error('An error occurred', new Error('Bad data')); // logged to console
// do other stuff
doSomthingWithTheLog(logger.getLogs()); // Only errors are retained and returned

Properties

| Property | Type | Access | Description | | -------- | ---- | ------ | ----------- | | severity | Logger.Severity | get | The Logger.Severity level |

Methods

getLogs(severity)

Get the logged messages

| Parameter | Type | Default | Description | | --------- | ---- | ------- | ----------- | | severity | Logger.Severity | The retain severity | The minimum severity level. If not given falls back on the retain severity level passed when the Logger was instantiated |

Example

const Logger = require('@evokegroup/logger');
const logger = new Logger(Logger.Severity.Error, { retain: Logger.Severity.Debug });
logger.info('Doing something'); // not logged to console
logger.debug('Data', { firstName: 'John', lastName: 'Doe' }); // not logged to console
logger.error('An error occurred', new Error('Bad data')); // logged

const allRetainedLogs = logger.getLogs();
/*
  [{
    severity: 2, logged: false, date: '2021-02-07T16:43:32.233Z', messages: ['Doing something']
  }, {
    severity: 3, logged: false, date: '2021-02-07T16:43:32.233Z', messages: ['Data', { firstName: 'John', lastName: 'Doe' }]
  }, {
    severity: 0, logged: true, date: '2021-02-07T16:43:32.233Z', messages: ['An error occurred', Error: Bad data)]
  }]
*/

const noDebug = logger.getLogs(Logger.Severity.Info);
/*
  noDebug = [{
    severity: 2, logged: false, date: '2021-02-07T16:43:32.233Z', messages: ['Doing something']
  }, {
    severity: 0, logged: true, date: '2021-02-07T16:43:32.233Z', messages: ['An error occurred', Error: Bad data)]
  }]
*/

debug(message[, ...message])

Log messages with a Logger.Severity.Debug severity level and using console.debug.

| Parameter | Type | Default | Description | | --------- | ---- | ------- | ----------- | | messages | * | | The messages to log |

Example

const Logger = require('@evokegroup/logger');

const logger_1 = new Logger(Logger.Severity.Debug);
logger_1.debug('Details', { firstName: 'John', lastName: 'Doe' });
// Expected output:
// Details
// { firstName: 'John', lastName: 'Doe' }

const logger_2 = new Logger(Logger.Severity.Error);
logger_2.debug('Details', { firstName: 'John', lastName: 'Doe' }); // This message will not be logged since the logger's maximum severity level is less than Logger.Severity.Debug

error(message[, ...message])

Log messages with a Logger.Severity.Error severity level and using console.error.

| Parameter | Type | Default | Description | | --------- | ---- | ------- | ----------- | | messages | * | | The messages to log |

info(message[, ...message])

Log messages with a Logger.Severity.Info severity level and using console.info.

| Parameter | Type | Default | Description | | --------- | ---- | ------- | ----------- | | messages | * | | The messages to log |

log(severity, message[, ...message])

Log messages

| Parameter | Type | Default | Description | | --------- | ---- | ------- | ----------- | | severity | Logger.Severity, number, string | Logger.Severity.Disabled | The message severity level | | messages | * | | The messages to log |

Example

const Logger = require('@evokegroup/logger');

const logger = new Logger(Logger.Severity.Error);
logger.log(Logger.Severity.Error, 'Error');
// Expected output:
// Error

warn(message[, ...message])

Log messages with a Logger.Severity.Warning severity level and using console.warn.

| Parameter | Type | Default | Description | | --------- | ---- | ------- | ----------- | | messages | * | | The messages to log |

Enumeration: Logger.Severity

| Property | Value | | -------- | ----- | | Disabled | -1 | | Error | 0 | | Warning | 1 | | Info | 2 | | Debug | 3 |