🚀 Overview

@typepurify/logger is a blazing-fast logger designed for backend services. It natively supports JSON serialization (preventing circular reference crashes) and includes middleware for Express.js.

📦 Installation

npm install @typepurify/logger

🛠 Features & Examples

1. Base Logger

Create a logger with JSON or colorized text formatting.

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

const log = new Logger({
  level: 'info',
  format: 'json', // or 'text'
  colorize: true,
  customColors: { info: '\x1b[36m' }, // Override ANSI colors (v0.5.11 🚀)
});

log.info('Server started', { port: 3000 });
log.error('Database connection failed', new Error('Timeout'));

2. Scoped Loggers

Create child loggers that automatically inherit properties.

import { createScopedLogger } from '@typepurify/logger';

const dbLogger = createScopedLogger(log, 'Database');
dbLogger.info('Query executed', { time: '10ms' });
// Outputs JSON with { "scope": "Database", "time": "10ms" } attached

3. Express Middleware

Automatically log incoming HTTP requests and response times.

import express from 'express';
import { requestLogger } from '@typepurify/logger';

const app = express();
app.use(requestLogger(log));

4. Utilities

• formatError(err): Beautifully formats stack traces.
• LogRateLimiter: Prevent your logs from being flooded during high-throughput errors (e.g. while in a retry loop).
• createFileLogger(path, options): File-backed logger stub.

5. Silent Mode

Easily suppress logs during test environments or specific runs.

const log = new Logger({
  silent: true,
});

🆕 New in v0.5.8

createLogAlertEngine() — Pattern-Based Log Alerting

Fires registered handler callbacks when log messages match defined RegExp rules.

import { createLogAlertEngine } from '@typepurify/logger';

const engine = createLogAlertEngine();
engine.addRule(/ERROR/, (msg) => sendAlert(msg));
engine.evaluate('ERROR: Database unreachable'); // triggers alert
engine.evaluate('INFO: Server started'); // no-op

formatLogWasm(level, message, meta?) — WASM Log Formatter

Fast structured log line formatter with ISO timestamp and meta serialization.

import { formatLogWasm } from '@typepurify/logger';

const line = formatLogWasm('error', 'DB timeout', { db: 'postgres' });
// "[WASM:ERROR] 2026-08-07T... - DB timeout | {"db":"postgres"}"

🛡️ License

MIT © Vallarasu Kanthasamy

📋 Changelog

v0.5.4 — Latest

New Features:

• injectOpenTelemetryTraceHeader(traceId, spanId) — Generates a W3C-compliant traceparent header object for distributed tracing with OpenTelemetry.

import { injectOpenTelemetryTraceHeader } from '@typepurify/logger';

const headers = injectOpenTelemetryTraceHeader(
  '4bf92f3577b34da6a3ce929d0e0e4736',
  '00f067aa0ba902b7',
);
// => { traceparent: '00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01' }

fetch('/api/endpoint', { headers });

Bug Fixes:

• Added maxBuffer cap to LogRateLimiter to prevent unbounded memory growth during log spikes.

v0.5.1

• Added silent mode for quiet test environments.
• Added sanitizeLogMeta to redact sensitive fields (password, token, secret, etc.).
• Added createNoopLogger for test stubs.
• Added createScopedLogger for tagged context logging.

0.5.8 Updates

Includes new features.