@philiprehberger/ts-logger

Structured JSON logger with child loggers, redaction, and pretty dev output.

Installation

npm install @philiprehberger/ts-logger

Usage

Basic

import { createLogger } from '@philiprehberger/ts-logger';

const logger = createLogger({ name: 'api', level: 'info' });

logger.info('Server started', { port: 3000 });
// {"level":"info","name":"api","msg":"Server started","port":3000,"ts":"2026-03-09T..."}

logger.error('Request failed', { status: 500, path: '/api/users' });

Log Levels

trace → debug → info → warn → error → fatal → silent

Messages below the configured level are silently dropped. Use silent to disable all output (useful in tests).

Child Loggers

const reqLogger = logger.child({ requestId: 'abc-123' });
reqLogger.info('Processing request');
// {"level":"info","name":"api","msg":"Processing request","requestId":"abc-123","ts":"..."}

const dbLogger = reqLogger.child({ service: 'database' });
// Inherits requestId + adds service

Auto-Redaction

Sensitive fields are automatically masked:

logger.info('Auth', { token: 'secret123', user: 'alice' });
// {"level":"info","name":"api","msg":"Auth","token":"[REDACTED]","user":"alice","ts":"..."}

Default redacted patterns: password, token, secret, authorization, cookie, key, credential, api_key, access_token, refresh_token, private_key.

Custom patterns:

const logger = createLogger({
  name: 'app',
  redact: ['ssn', 'credit_card', 'password'],
});

Arrays are redacted recursively:

logger.info('Users', { users: [{ name: 'alice', token: 'abc' }] });
// token is redacted inside the array element

Circular references are handled safely:

const obj: any = { name: 'test' };
obj.self = obj;
logger.info('Circular', obj);
// self becomes "[Circular]"

Disable redaction:

const logger = createLogger({ name: 'app', redact: false });

Pretty Mode

Auto-detected in development (NODE_ENV=development), or set manually:

const logger = createLogger({ name: 'app', pretty: true });
// INFO  [app] Server started {"port":3000}

Runtime Level Changes

const logger = createLogger({ name: 'app', level: 'info' });
logger.debug('hidden'); // dropped

logger.setLevel('debug');
logger.debug('now visible'); // logged

// Child loggers inherit the parent's level unless they set their own
const child = logger.child({ req: '123' });
logger.setLevel('error'); // child also uses 'error' now
child.setLevel('debug');  // child overrides to 'debug'

Environment Variables

• LOG_LEVEL — sets the log level (overrides constructor option, case-insensitive)
• NODE_ENV=development — enables pretty mode by default

Custom Colors

import { consoleTransport } from '@philiprehberger/ts-logger';

const transport = consoleTransport({
  pretty: true,
  colors: { error: '\x1b[41m', info: '\x1b[36m' },
});

Development

npm install
npm run build
npm test

License

MIT