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Logstory

A flexible and extensible logger for JavaScript/TypeScript with middleware support and configurable log levels.

Installation

npm install @37bytes/logstory

Features

• Scopes
• Configurable log levels
• Middleware support for integration with Sentry, Graylog, etc.
• Works everywhere (client, server)
• Lightweight (~5KB)

Quick Start

import { createLogstory } from '@37bytes/logstory';

const logger = createLogstory({
  name: 'Scope',
  logLevelConfig: {
    debug: process.env.NODE_ENV === 'development',
    log: true,
    warn: true,
    error: true
  }
});

logger.debug('Debug message');  // Only in dev mode
logger.log('Info message');
logger.warn('Warning message');
logger.error('Error message');

API

createLogstory(options)

Parameters

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | name | string | undefined | Logger name, displayed in output | | logLevelConfig | Partial<LogLevelConfig> | All true | Which log levels are enabled | | consoleProxy | Console | globalThis.console | Custom console implementation (for middleware) | | formatLoggerName | Function | Default | Logger name formatting function |

LogLevelConfig

type LogLevelConfig = {
  debug: boolean;
  log: boolean;
  warn: boolean;
  error: boolean;
};

Note: logLevelConfig is Partial, meaning you can specify only the levels you want to override. Unspecified levels will use their default values (all true).

Example:

// Only disable debug, keep others enabled
const logger = createLogstory({
  name: 'MyApp',
  logLevelConfig: { debug: false }  // log, warn, error remain true
});

Custom Formatting

const logger = createLogstory({
  name: 'MyApp',
  formatLoggerName: ({ loggerName, logLevel }) => {
    if (logLevel === 'error') {
      return `🔥 [${loggerName}]: %o`;
    }
    return `[${loggerName}]: %o`;
  }
});

logger.error('Critical error'); // 🔥 [MyApp] Critical error

Advanced Usage

Sentry Integration

You can extend the logger with additional methods for monitoring:

import { createLogstory } from '@37bytes/logstory';
import * as Sentry from '@sentry/browser';

const createLogger = (name: string) => {
  const logger = createLogstory({ name });
  
  logger.error.withSentry = (error, context) => {
    logger.error(error);
    Sentry.captureException(error, { extra: context });
  };

  return logger;
};

const logger = createLogger('PaymentService');
logger.error.withSentry(new Error('Payment failed'), { userId: '123' });

Changelog

2.0.0

• Node.js support
• Migrated to tsup (CommonJS + ESM)
• Renamed createLogger → createLogstory
• Renamed logLevelState → logLevelConfig

1.0.0

• Initial release

License

MIT