logger-utility

A simple, singleton-pattern-based logging utility using winston and winston-daily-rotate-file for rotating log files daily with convenient log management.

Features

• Singleton logger instance for consistent logging
• Logs to console and daily rotated log files
• Customizable log directory
• Supports multiple log levels: info, warn, error, debug, fatal
• Automatically creates log directory if missing

Installation

npm install logger-utility

Usage

const { LoggerUtil } = require("logger-utility");

const logger = LoggerUtil.getInstance();

logger.log("info", "This is an info message");
logger.log("error", "This is an error message");

Important Notes

Singleton Pattern

• Only one instance of the logger exists during the app lifecycle.
• Access the logger only via the LoggerUtil.getInstance() method.
• Do not instantiate LoggerUtil directly.

What to do

const logger = LoggerUtil.getInstance();
logger.log("info", "Logging an informational message");

What NOT to do

1. Instantiating LoggerUtil directly (breaks singleton):

// ❌ Avoid this!
const logger = new LoggerUtil(); // Will break singleton pattern or throw error
logger.log("info", "This is incorrect usage");

2. Detaching log method from instance (loses this context):

const logger = LoggerUtil.getInstance();

const log = logger.log;
log("info", "This will not work correctly because `this` is undefined inside log");

Always call log via the instance:

logger.log("info", "Correct usage");

3. Creating multiple instances manually:

// ❌ Avoid multiple instances manually
const logger1 = LoggerUtil.getInstance();
const logger2 = LoggerUtil.getInstance();

// Both are same instance (good)
// But do NOT do:
const badLogger = new LoggerUtil(); // Don't do this

API

LoggerUtil.getInstance()

Returns the singleton instance of the logger.

logger.log(level: LogLevel, message: string): void

Logs a message at the specified log level.

• level: One of "info" | "warn" | "error" | "debug" | "fatal"
• message: Log message string

License

MIT License © [SURAJ]

Author

[SURAJ] — [email protected]
GitHub: https://github.com/suraj-o