Logger

A lightweight and flexible logging library for Node.js applications, providing file-based logging with timestamp formatting and timezone support.

Installation

npm install @supercat1337/logger

Features

• 📝 Simple file-based logging with different log levels
• 🕒 Configurable timestamp formatting with timezone support
• 📁 Automatic log file path conversion utilities
• 🚀 Promise-based async logging operations
• 🔧 Customizable output directory and file extensions
• ✅ TypeScript support with full type definitions

Quick Start

import { Logger } from '@supercat1337/logger';

// Create a logger instance
const logger = new Logger('./app.log');

// Log messages at different levels
await logger.info('Application started');
await logger.warn('Low disk space');
await logger.error('Failed to connect to database');

// Close the logger when done
await logger.close();

API Reference

Logger Class

The main Logger class for writing log messages to files.

Constructor

new Logger(filePath: string, options?: {
    useDate?: boolean;
    timeZone?: any;
})

• filePath: Path to the log file
• options.useDate: Whether to include timestamps in log messages (default: true)
• options.timeZone: Timezone for timestamps

Methods

• log(message: string, level?: string): Promise<void> - Write a log message with specified level
• error(message: string): Promise<void> - Write an error message
• warn(message: string): Promise<void> - Write a warning message
• info(message: string): Promise<void> - Write an info message
• close(): Promise<boolean> - Close the logger and wait for pending writes

Utility Functions

convertFilePathToLogFilePath()

Convert a file path to a log file path by appending .log extension.

convertFilePathToLogFilePath(
    filePath: string, 
    suffix?: string, 
    options?: {
        outputDir?: string;
        extension?: string;
    }
): string

Date Formatting Functions

• formatDate(date: Date, format?: string, timeZone?: string): string - Format a date with custom format and timezone
• getDateString(timeZone?: string): string - Get current date as YYYY-MM-DD
• getDateTimeString(timeZone?: string): string - Get current datetime as YYYY-MM-DD HH:MM:SS
• getDateTimeStringForFileName(timeZone?: string): string - Get datetime for filenames as YYYY-MM-DD_HH-MM-SS
• getCurrentTimeZone(): string - Get current system timezone

Usage Examples

Basic Logging

import { Logger } from '@supercat1337/logger';

const logger = new Logger('./logs/app.log');

// Log with different levels
await logger.info('User logged in');
await logger.warn('API response slow');
await logger.error('Database connection failed');

// Custom log level
await logger.log('Debug message', 'debug');

With Timezone Configuration

import { Logger } from '@supercat1337/logger';

// Logger with specific timezone
const logger = new Logger('./app.log', {
    useDate: true,
    timeZone: 'America/New_York'
});

await logger.info('Log with New York timezone');

File Path Conversion

import { convertFilePathToLogFilePath } from '@supercat1337/logger';

// Convert source file path to log file path
const logPath = convertFilePathToLogFilePath('/src/app.js');
// Returns: /src/app.js.log

// With custom output directory and suffix
const customLogPath = convertFilePathToLogFilePath(
    '/src/app.js',
    'errors',
    { outputDir: '/logs', extension: '.txt' }
);
// Returns: /logs/app.errors.txt

Date Formatting

import { 
    getDateString, 
    getDateTimeString,
    formatDate 
} from '@supercat1337/logger';

// Get formatted dates
const today = getDateString(); // "2024-01-15"
const now = getDateTimeString(); // "2024-01-15 14:30:45"

// Custom formatting
const customDate = formatDate(
    new Date(), 
    'YYYY/MM/DD HH:mm:ss',
    'Europe/London'
);

Error Handling

The logger handles write errors gracefully:

try {
    await logger.error('Something went wrong');
} catch (err) {
    console.error('Failed to write log:', err);
}

Closing the Logger

Always close the logger to ensure all pending writes are completed:

// In an async context
await logger.close();

// Or with then/catch
logger.close()
    .then(() => console.log('Logger closed'))
    .catch(err => console.error('Error closing logger:', err));

License

MIT