@veksa/logger

Lightweight, configurable logging library for JavaScript applications

Installation

@veksa/logger requires TypeScript 5.8 or later.

Using npm or yarn

# npm
npm install @veksa/logger

# yarn
yarn add @veksa/logger

Features

• Enhanced console logging with timestamps
• Memory storage of logs with automatic expiration (10 minutes by default)
• Special formatting for requests, responses, and events
• Easy enabling/disabling of logging
• Support for restricting specific message IDs
• Colorized console output
• Generic type support for type-safe message handling
• Utility functions for log management

Basic Usage

import { createLogger } from '@veksa/logger';

// Create logger (enabled by default)
const logger = createLogger(true);

// Basic logging
logger.info('Application started');
logger.warn('Resource is running low');
logger.error('Failed to connect', { code: 500 });

// Network message logging
logger.request({
  id: 'GET_USER',
  payload: { userId: 123 },
  clientMsgId: 'abc-123'
}, {
  prefix: 'API',
  messageName: 'GetUser'
});

logger.response({
  id: 'GET_USER',
  payload: { user: { id: 123, name: 'John' } },
  clientMsgId: 'abc-123'
}, {
  prefix: 'API',
  messageName: 'GetUser'
});

// Get all stored logs
const logs = logger.getLogs();

// Disable logging
logger.disable();

// Enable logging
logger.enable();

API Reference

createLogger<Message>(isEnabled, isRestricted?)

Creates a new logger instance.

• isEnabled (boolean): Whether logging is initially enabled
• isRestricted (function): Optional function that determines if a message ID should be restricted from logging

Returns an ILogger<Message> object with the following methods:

Methods

• enable(): Enable console output
• disable(): Disable console output
• getLogs(): Get array of stored log items
• info(text, ...causes): Log informational message
• error(text, ...causes): Log error message
• warn(text, ...causes): Log warning message
• request(item, meta?): Log request with optional metadata
• response(item, meta?): Log response with optional metadata
• event(item, meta?): Log event with optional metadata

Interfaces

interface ILogItem {
    timestamp: number;
    message: string;
}

interface IMessage<Payload = unknown> {
    id?: string | number;
    payload: Payload;
    clientMsgId: string;
}

interface IMessageMeta {
    prefix?: string;
    prefixColor?: string;
    messageName?: string;
}

interface ILogger<Message extends IMessage> {
    enable: () => void;
    disable: () => void;
    getLogs: () => ILogItem[];
    info: (text: string, ...causes: unknown[]) => void;
    error: (text: string, ...causes: unknown[]) => void;
    warn: (text: string, ...causes: unknown[]) => void;
    request: (item: Message, meta?: IMessageMeta) => void;
    response: (item: Message, meta?: IMessageMeta) => void;
    event: (item: Message, meta?: IMessageMeta) => void;
}

Helper Functions

mergeLogs(limit)

Merges multiple log arrays into a single array, sorted by timestamp.

• limit (number): Maximum number of log messages to return

import { createLogger, mergeLogs } from '@veksa/logger';

const logger1 = createLogger(true);
const logger2 = createLogger(true);

// Get combined logs from both loggers, limited to 100 entries
const combinedLogs = mergeLogs(100)(logger1.getLogs(), logger2.getLogs());

Contributing

This project welcomes contributions and suggestions.

License

MIT