Custom Logger

Description

A highly customizable, feature-rich logging library with configurable levels, colors, icons, timestamps, and context-aware logging. Perfect for both development and production environments.

Features

• 🎨 Colorful output with ANSI colors (configurable)
• 📊 Custom log levels with numeric priorities
• ⏱️ Timestamps with millisecond precision
• 🏷️ Context-specific loggers for different modules
• 🎯 Level filtering to control verbosity
• 🔧 Fully configurable format, colors, and behavior
• 📝 Object/JSON support with pretty printing
• 🚀 Zero dependencies
• 📦 ESM & CJS support

Installation

npm install -D @m00nbyte/custom-logger
yarn add -D @m00nbyte/custom-logger

Usage

import logger from '@m00nbyte/custom-logger';

// Basic usage
logger.debug('Debug message');
logger.info('Info message');
logger.warn('Warning message');
logger.error('Error message');
logger.success('Success!');
logger.update('Config updated');

// Function style (legacy)
logger('info', 'Function style logging');

// With objects
logger.info({ user: 'john', action: 'login', timestamp: new Date() });

Configuration

Global Configuration

import logger from '@m00nbyte/custom-logger';

// Configure logger
logger.configure({
    level: 2, // Only show warn and above (0-4)
    colored: true, // Enable colored output
    icons: true, // Show emoji icons
    timestamp: true, // Show timestamps
    format: '❱ %timestamp% ❱ %icon%%event% ❱ %message%',
    silentInit: false // Log configuration changes
});

// Individual settings
logger.setLevel(3); // Set log level (0=all, 3=errors only)
logger.colored(true); // Enable/disable colors
logger.icons(false); // Enable/disable icons
logger.timestamp(true); // Enable/disable timestamps

Available Log Levels

| Level | Numeric Value | Default Color | Default Icon | Description | | ------- | ------------- | ------------- | ------------ | -------------------------- | | debug | 0 | grey | 🔧 | Detailed debug information | | update | 0 | cyan | 🔄 | Configuration updates | | info | 1 | blue | ℹ️ | General information | | success | 1 | green | ✅ | Success messages | | warn | 2 | yellow | ⚠️ | Warnings | | error | 3 | red | ❌ | Errors |

Advanced Usage

Custom Log Levels

// Add custom log level
logger.addLevel('critical', {
    color: 'magenta',
    level: 4,
    icon: '💥'
});

// Use custom level
logger('critical', 'System critical!');

// Update existing level
logger.updateLevel('warn', {
    newName: 'warning',
    color: 'cyan',
    level: 2
});

// Remove a level
logger.removeLevel('debug');

// List all available levels
logger.listLevels();

Context-Specific Loggers

Create dedicated loggers for different parts of your application:

// Create module-specific loggers
const apiLogger = logger.create('API');
const dbLogger = logger.create('Database');
const authLogger = logger.create('Auth');

// Use them with automatic context prefix
apiLogger.info('Request started');
// Output: ❱ 14:30:25.123 ❱ API:info ❱ Request started

dbLogger.warn('Slow query detected');
// Output: ❱ 14:30:25.456 ❱ Database:warn ❱ Slow query detected

authLogger.error('Invalid credentials');
// Output: ❱ 14:30:25.789 ❱ Auth:error ❱ Invalid credentials

Custom Format Templates

Customize the output format with placeholders:

logger.configure({
    format: '[%time%] %event% - %message%'
});

// Available placeholders:
// %timestamp% - Full timestamp (HH:MM:SS.mmm)
// %date% - Date only (YYYY-MM-DD)
// %time% - Time only (HH:MM:SS)
// %event% - Event/level name
// %icon% - Emoji icon (if enabled)
// %level% - Numeric level
// %message% - The log message

Level Filtering Examples

// Show all messages (default)
logger.setLevel(0);
// Shows: debug, update, info, success, warn, error

// Show informational and above
logger.setLevel(1);
// Shows: info, success, warn, error, update

// Show warnings and above
logger.setLevel(2);
// Shows: warn, error, update

// Show errors only
logger.setLevel(3);
// Shows: error, update

// Show nothing (except updates)
logger.setLevel(4);
// Shows: update only

API Reference

Core Methods

// Direct logging methods
logger.debug(message: string | object)
logger.info(message: string | object)
logger.warn(message: string | object)
logger.error(message: string | object)
logger.success(message: string | object)
logger.update(message: string | object)

// Function-style logging
logger(type: string, message: string | object)

// Configuration
logger.configure(options: LoggerOptions)
logger.setLevel(level: number)
logger.getLevel(): number
logger.colored(enabled: boolean)
logger.icons(enabled: boolean)
logger.timestamp(enabled: boolean)

// Level Management
logger.addLevel(name: string, config: LevelConfig)
logger.updateLevel(oldName: string, options: UpdateOptions)
logger.removeLevel(name: string)
logger.hasLevel(name: string): boolean
logger.listLevels(): void

// Context Loggers
logger.create(context: string): ContextLogger

Available Colors

• black
• red
• green
• yellow
• blue
• magenta
• cyan
• white
• grey

Examples

Production Configuration

import logger from '@m00nbyte/custom-logger';

// Production settings - minimal output
if (process.env.NODE_ENV === 'production') {
    logger.configure({
        level: 2, // Only warnings and errors
        colored: false, // No colors in production
        icons: false, // No emojis
        timestamp: true, // Keep timestamps for debugging
        silentInit: true // No init logs
    });
}

// Development settings - verbose output
if (process.env.NODE_ENV === 'development') {
    logger.configure({
        level: 0, // Show everything
        colored: true, // Colors for readability
        icons: true, // Fun emojis
        timestamp: true, // Helpful timestamps
        format: '❱ %timestamp% ❱ %icon%%event% ❱ %message%'
    });
}

Error Tracking Integration

import logger from '@m00nbyte/custom-logger';

const errorLogger = logger.create('Errors');

// Integrate with error tracking service
const originalError = logger.error;

logger.error = function (message) {
    // Send to error tracking service
    if (typeof message === 'object' && message.error) {
        sendToErrorService(message.error);
    }

    // Call original logger
    originalError.call(this, message);
};

// Usage
try {
    riskyOperation();
} catch (error) {
    errorLogger.error({ error, context: 'riskyOperation' });
}

Browser Support

The logger works in both Node.js and modern browsers. For browser usage, include it in your build process:

<script src="https://cdn.jsdelivr.net/gh/m00nbyte/custom-logger@latest/dist/index.iife.min.js"></script>
<script>
    window.customLogger.info('Hello from browser!');
</script>

Performance

The logger is designed to be performant:

• Conditional output based on log level
• Minimal overhead when logging is disabled
• Efficient string formatting
• Zero dependencies

Contribution

Feel free to submit issues or pull requests.

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Changelog

License