wlg - NodeJS/Deno logger suite

Features

• Small, easy to understand and easy to use
• Javascript/Typescript compatible
• Context properties (e.g. servicename, requestId, etc)
• State properties (e.g. request-data). Not logged, usable by Transports
• Dynamically add/remove transports
• Child-loggers
• Async transports
• Flush() method (for at the end of your lambdas)

Setup and basic logging

import { Logger, logLevel, TransportConsole, logFormatCompact } from 'wlg';

const log = new Logger(
  { service: 'test' },
  {
    transports: {
      shortConsole: new TransportConsole(logLevel.debug, {
        formatter: logFormatCompact,
      }),
    },
  },
);

// basis usage
log.info('some string', { extra_opt1: 'something_else' });

// child logging
//  requestId becomes context (and is printed, logged)
//  rq: becomes state (not printed, but available for transports)
childLogger = log.child({ requestId: 'my-request-id' }, { rq: ctx.rq });
childLogger.info('some string for the request', { extra: 'args' });

// Flush transports before closing (a lambda)
await log.flush(1000);

API references for the Logger class

• .trace|debug|verbose|info|warn|error|fatal(msg, obj|Error)

Logs a message with optional extra|error properties.

• .transports()

Returns list of transport-names currently in use by the logger

• .transportAdd(name, transport)

Add a new transport to the Logger, will throw if a transport with that name already exists.

• .transportRemove(name)

Remove a transport from the Logger

• .contextSet(obj)

Adds obj to the logger context

• .stateAdd(obj)

Adds obj to the logger state

• .child(objContext, objState)

Create a child logger with extra context properties (objContext) and state (objState) When a line gets logged through the child logger the state and context of the child logger is merged with the main logger.

API Reference for other exported data

• logLevelByStr(string)

Returns logLevel enum value for given string. Will throw on unknown loglevel.

• logLevel

Enum with all the loglevels

• LogTransport

Base LogTransport implementation

• TransportConsole

Basic console output transport

• logFormatCompact

Compact formatter

• logFormatJson

JSON formatter