dtducas-smart-log

A smart logging package with environment-aware log levels for Node.js applications.

Features

• Environment-aware logging (Development vs Production)
• Multiple log levels: info, warn, error, debug
• Automatic timestamp formatting
• TypeScript support with full type definitions
• Zero dependencies
• Easy configuration
• Singleton pattern with factory function support

Installation

npm install dtducas-smart-log

Quick Start

import smartLog from "dtducas-smart-log";

// Basic usage - replaces console.log
smartLog.info("Application started");
smartLog.warn("This is a warning");
smartLog.error("An error occurred");
smartLog.debug("Debug information");

Environment Behavior

Development Environment (NODE_ENV=development)

All log levels are enabled:

• smartLog.info() - Logged
• smartLog.warn() - Logged
• smartLog.error() - Logged
• smartLog.debug() - Logged

Production Environment (NODE_ENV=production)

Only error logs are enabled:

• smartLog.info() - Not logged
• smartLog.warn() - Not logged
• smartLog.error() - Logged
• smartLog.debug() - Not logged

Log Format

All logs are formatted with timestamp and log level:

[2025-11-02T10:30:45.123Z] [INFO] Your log message here
[2025-11-02T10:30:45.456Z] [ERROR] Error message here

API Documentation

Default Import (Singleton)

import smartLog from "dtducas-smart-log";

smartLog.info("message", optionalArgs);
smartLog.warn("message", optionalArgs);
smartLog.error("message", optionalArgs);
smartLog.debug("message", optionalArgs);

Methods

info(message: string, ...args: any[]): void

Log informational messages. Only works in development environment.

smartLog.info("User logged in", { userId: 123 });

warn(message: string, ...args: any[]): void

Log warning messages. Only works in development environment.

smartLog.warn("API rate limit approaching", { remaining: 10 });

error(message: string, ...args: any[]): void

Log error messages. Works in both development and production environments.

smartLog.error("Database connection failed", error);

debug(message: string, ...args: any[]): void

Log debug messages. Only works in development environment.

smartLog.debug("Processing request", { data: payload });

Configuration

configure(config: SmartLogConfig): void

Update logger configuration at runtime.

smartLog.configure({
  environment: "production",
  disableAll: false,
});

Configuration Options

interface SmartLogConfig {
  environment?: "development" | "production" | string;
  disableAll?: boolean;
  timestampFormat?: "iso" | "locale" | "custom";
  customTimestampFormatter?: () => string;
}

Advanced Usage

Creating Custom Logger Instances

import { createLogger } from "dtducas-smart-log";

const customLogger = createLogger({
  environment: "production",
  disableAll: false,
});

customLogger.error("This will be logged");
customLogger.info("This will NOT be logged in production");

Disabling All Logs

import smartLog from "dtducas-smart-log";

// Disable all logs including errors
smartLog.configure({ disableAll: true });

smartLog.error("This will not be logged");
smartLog.info("This will not be logged");

Custom Timestamp Format

import smartLog from "dtducas-smart-log";

// Use locale format
smartLog.configure({ timestampFormat: "locale" });

// Use custom formatter
smartLog.configure({
  timestampFormat: "custom",
  customTimestampFormatter: () => {
    return new Date().toISOString().split("T")[0]; // YYYY-MM-DD
  },
});

TypeScript Support

Full TypeScript support with exported types:

import smartLog, {
  LogLevel,
  Environment,
  SmartLogConfig,
  SmartLogger,
} from "dtducas-smart-log";

const config: SmartLogConfig = {
  environment: Environment.PRODUCTION,
  disableAll: false,
};

smartLog.configure(config);

Examples

Express.js Application

import express from "express";
import smartLog from "dtducas-smart-log";

const app = express();

app.get("/", (req, res) => {
  smartLog.info("Homepage accessed");
  res.send("Hello World");
});

app.use((err, req, res, next) => {
  smartLog.error("Unhandled error", err);
  res.status(500).send("Internal Server Error");
});

app.listen(3000, () => {
  smartLog.info("Server started on port 3000");
});

Migration from console.log

Before:

console.log("User logged in:", userId);
console.error("Error:", error);
console.warn("Warning:", message);

After:

import smartLog from "dtducas-smart-log";

smartLog.info("User logged in:", userId);
smartLog.error("Error:", error);
smartLog.warn("Warning:", message);

Environment Variables

The package automatically detects the environment using process.env.NODE_ENV:

# Development (all logs enabled)
NODE_ENV=development node app.js

# Production (only errors enabled)
NODE_ENV=production node app.js

License

MIT

Author

Duong Tran Quang (DTDucas) Email: [email protected]

Repository

https://github.com/dtducas/dtducas-smart-log

Issues

Report issues at: https://github.com/dtducas/dtducas-smart-log/issues