logger-standard 🚀

A flexible and feature-rich logging utility for Node.js applications.

Features ✨

• 🎨 Service Prefixes - Tag logs with service names
• 📅 Timestamps - Optional timestamp display
• 🎯 Log Levels - Control verbosity (debug, info, warn, error)
• 🚀 Emojis - Optional visual indicators (disabled by default)
• 📊 Structured Logging - JSON output for log aggregation
• 📏 Indentation - Hierarchical log formatting
• 👶 Child Loggers - Create scoped loggers
• 📈 Metrics - Built-in metrics logging
• 🎨 Colored Output - Using console-error, console-info, console-warn

Installation

npm install logger-standard

Quick Start

import { Logger } from 'logger-standard';

// Basic usage (no emojis, backward compatible)
const logger = new Logger({ service: 'my-app' });

logger.info('Server started');
// [my-app] Server started

logger.error('Connection failed');
// [my-app] Connection failed

API

Constructor Options

| Option | Type | Default | Description | |--------|------|---------|-------------| | service | string | "" | Service name prefix | | showDate | boolean | false | Show timestamps | | useEmojis | boolean | false | Enable emoji indicators | | logLevel | string | "info" | Minimum log level (debug, info, warn, error) | | indentLevel | number | 0 | Initial indentation level | | prefix | string | "" | Additional prefix |

Basic Methods

logger.log(message, sensorId?)      // Generic log
logger.debug(message, sensorId?)    // Debug level
logger.info(message, sensorId?)     // Info level
logger.warn(message, sensorId?)     // Warning level
logger.error(message, sensorId?)    // Error level

Emoji Methods (require useEmojis: true)

logger.success(message)             // ✅ Success (if emojis enabled)
logger.failure(message)             // ❌ Failure (if emojis enabled)
logger.warning(message)             // ⚠️  Warning (if emojis enabled)
logger.start(message)               // 🚀 Start (if emojis enabled)
logger.stop(message)                // 🛑 Stop (if emojis enabled)
logger.step(message, important?)    // → or ⭐ Step (if emojis enabled)

Advanced Methods

logger.indent(level)                // Set indentation level
logger.child({ prefix })            // Create child logger
logger.json(data)                   // Structured JSON log
logger.metric(key, value, unit?)    // Metrics logging

Usage Examples

Basic Usage (No Emojis)

import { Logger } from 'logger-standard';

const logger = new Logger({
  service: 'api',
  showDate: true
});

logger.info('Server started on port 3000');
// 04/05/2026 10:30:15 [api] Server started on port 3000

logger.warn('High memory usage detected');
// 04/05/2026 10:30:16 [api] High memory usage detected

logger.error('Database connection failed');
// 04/05/2026 10:30:17 [api] Database connection failed

With Emojis (Optional)

import { Logger } from 'logger-standard';

const logger = new Logger({
  service: 'pipeline',
  useEmojis: true  // Enable emojis
});

logger.start('Starting campaign pipeline');
// 🚀 [pipeline] Starting campaign pipeline

logger.step('Research phase', true);
// ⭐ [pipeline] Research phase

logger.success('ICP generated');
// ✅ [pipeline] ICP generated

logger.failure('API rate limited');
// ❌ [pipeline] API rate limited

With Indentation

const logger = new Logger({ service: 'leads' });

logger.info('Processing leads');
logger.indent(1).info('Loading from file');
logger.indent(2).info('Found 100 leads');
logger.indent(1).info('Filtering by score');
logger.indent(0).info('Complete');

// Output:
// [leads] Processing leads
// [leads]    Loading from file
// [leads]       Found 100 leads
// [leads]    Filtering by score
// [leads] Complete

With Log Levels

const logger = new Logger({
  service: 'api',
  logLevel: 'warn'  // Only show warn and error
});

logger.debug('Debug info');         // Not shown
logger.info('Request received');    // Not shown
logger.warn('Slow query detected'); // [api] Slow query detected
logger.error('Connection failed');  // [api] Connection failed

Child Loggers

const apiLogger = new Logger({ service: 'api' });

const authLogger = apiLogger.child({ prefix: 'auth' });
const dbLogger = apiLogger.child({ prefix: 'db' });

authLogger.info('User authenticated');
// [api] [auth] User authenticated

dbLogger.warn('Connection pool low');
// [api] [db] Connection pool low

Structured Logging

const logger = new Logger({ service: 'analytics' });

logger.json({
  event: 'user_signup',
  userId: 'usr_123',
  plan: 'premium',
  referrer: 'google'
});

// Output (JSON):
// {"timestamp":"2026-04-05T10:30:15.000Z","service":"analytics","event":"user_signup","userId":"usr_123","plan":"premium","referrer":"google"}

Metrics Logging

const logger = new Logger({ service: 'api' });

logger.metric('response_time', 145, 'ms');
logger.metric('memory_usage', 512, 'MB');
logger.metric('active_connections', 42);

// Output (with emojis disabled):
// [api] METRIC response_time=145ms
// [api] METRIC memory_usage=512MB
// [api] METRIC active_connections=42

// With emojis enabled:
// 📊 [api] METRIC response_time=145ms

Sensor ID Tracking

const logger = new Logger({ service: 'iot' });

logger.info('Temperature reading', 'sensor-001');
// [iot] Temperature reading (sensorId: sensor-001)

logger.error('Connection lost', 'sensor-042');
// [iot] Connection lost (sensorId: sensor-042)

Log Levels

Control verbosity by setting the log level:

• debug - Detailed debugging information
• info - General informational messages (default)
• warn - Warning messages
• error - Error messages

const logger = new Logger({ logLevel: 'warn' });

logger.debug('Debug');  // Not shown (level too low)
logger.info('Info');    // Not shown (level too low)
logger.warn('Warning'); // Shown
logger.error('Error');  // Shown

Migration from 1.x

Version 2.0 is fully backward compatible. Your existing code works unchanged:

// v1.x code works perfectly
const logger = new Logger({ service: 'app', showDate: true });
logger.info('Hello');
logger.error('Error');

// New features are opt-in
const enhancedLogger = new Logger({
  service: 'app',
  showDate: true,
  useEmojis: true,     // NEW: Enable emojis
  logLevel: 'debug'    // NEW: Set log level
});

Breaking changes: None! All new features are optional.

Why logger-standard?

• ✅ Zero dependencies (except colored console packages)
• ✅ Lightweight (~200 LOC)
• ✅ Flexible - Use only what you need
• ✅ Backward compatible - Safe to upgrade
• ✅ Clean code - All functions ≤7 lines
• ✅ Production ready - Used in multiple projects

License

ISC

Contributing

Contributions, issues, and feature requests are welcome!

Repository

https://github.com/nivkman/logger-standard