Log-Vani

A robust and customizable logging library for Node.js applications. log-vani supports multiple log levels, customizable formats, color-coded output, JSON logging, and integration with custom log transports, making it suitable for both development and production environments.

Installation

Install log-vani using npm:

npm install log-vani

Usage

Basic Usage

const Logger = require("log-vani");

// Create a new Logger instance
const logger = new Logger({
  logFile: "path/to/your/logfile.log", // Path to the log file
});

// Log messages with different levels
logger.info("This is an info message");
logger.warn("This is a warning message");
logger.error("This is an error message");
logger.debug("This is a debug message");

Log Levels

• info: Informational messages
• warn: Warning messages
• error: Error messages
• debug: Debugging messages

Custom Log Formats

You can customize the log format using the format option. The default format is:

[{level}] {message} at {timestamp}

You can replace this format with your custom string containing placeholders:

• {level}: The log level (e.g., INFO, WARN, ERROR, DEBUG).
• {message}: The log message.
• {timestamp}: The current timestamp.

Example of Custom Format

const logger = new Logger({
  logFile: "path/to/your/logfile.log",
  format: "{level} - {message} at {timestamp} from {hostname}",
});

Color-Coded Logs

Each log level is color-coded for better readability in the terminal. The default colors are:

• info: Green
• warn: Yellow with Magenta background
• error: Red with White background
• debug: Cyan

You can customize the colors in the terminal output.

Custom Transport

You can send logs to external services (e.g., a logging server) using the customTransport option. The transport must implement a send method.

Example

const logger = new Logger({
  logFile: "path/to/your/logfile.log",
  customTransport: {
    send: function (log) {
      console.log("Sending log to external service:", log);
    },
  },
});

logger.info("This log will be sent to an external service");

JSON Logging

If you prefer logging in JSON format, you can use the logAsJson method. This is especially useful for log aggregation systems.

logger.logAsJson("info", "This is a JSON log entry");

Clearing Logs

Clear the log file using the clearLogs method. This is useful when you need to reset logs between runs.

logger.clearLogs();

Rate Limiting

Control the rate at which logs are written using the rateLimit option. This prevents spamming logs in high-frequency scenarios.

const logger = new Logger({
  rateLimit: 2000, // Minimum 2 seconds between logs
});

Full Example

const Logger = require("log-vani");

// Create a new Logger instance with full configuration
const logger = new Logger({
  logFile: "logs/app.log",
  rateLimit: 2000, // Log rate limiting in milliseconds
  format: "[{level}] {message} at {timestamp}",
  customTransport: {
    send: function (log) {
      // Send log to an external service
      console.log("Sending log:", log);
    },
  },
});

logger.info("Application started");
logger.warn("This is a warning");
logger.error("An error occurred");
logger.debug("Debugging details");
logger.logAsJson("info", "JSON formatted log entry");
logger.clearLogs();

API

new Logger(options)

Creates a new logger instance.

Options:

• logFile (string): Path to the log file. Default is test.log.
• rateLimit (number): Minimum time between log writes in milliseconds. Default is 1000ms.
• format (string): Custom format for log messages. Placeholders include {level}, {message}, {timestamp}.
• customTransport (object): An object with a send method for sending logs to external systems.

Methods:

• info(message): Logs an informational message.
• warn(message): Logs a warning message.
• error(message): Logs an error message.
• debug(message): Logs a debug message.
• logAsJson(level, message): Logs a message in JSON format.
• clearLogs(): Clears the log file.

Features

• Multiple Log Levels: Supports info, warn, error, and debug log levels.
• Custom Formats: Define custom formats for your log messages.
• Color-Coded Logs: Terminal output is color-coded for clarity.
• Custom Transport: Send logs to external systems.
• JSON Logging: Log entries in JSON format.
• File-Based Logging: Logs are written to a specified file.
• Rate Limiting: Prevent excessive log writes in high-frequency scenarios.
• Clear Logs: Reset the log file when needed.

License

MIT License