Logger-JS

Logger-JS is a lightweight logging utility for JavaScript (ES6) that provides various logging levels and supports NDJson formatting for structured logging.

Table of Contents

1. Installation
2. Importing the Library
3. Configuration
4. Logging Messages
5. NDJson Logging
6. Customization

Installation

To install Logger-JS, use npm to add it to your project:

npm i --save @rabbit-company/logger

Importing the Library

After installation, you can import the Logger into your JavaScript file:

import Logger from "@rabbit-company/logger";

Configuration

Configure the logger to suit your needs. You can set the log level to control which types of messages are logged:

// Set the log level to SILLY to enable all levels of logging
Logger.level = Logger.Levels.SILLY;

// Enable or disable colored output
Logger.colors = true; // Set to false to disable colors

// Enable or disable NDJson logging
Logger.NDJson = false; // Set to true to enable NDJson logging

Logging Messages

Use the provided methods to log messages at different levels of severity:

// Log an error message
Logger.error("This is an error message.");

// Log a warning message
Logger.warn("This is a warning message.");

// Log an informational message
Logger.info("This is an informational message.");

// Log an HTTP-related message
Logger.http("This is an HTTP-related message.");

// Log a verbose message
Logger.verbose("This is a verbose message.");

// Log a debug message
Logger.debug("This is a debug message.");

// Log a silly message
Logger.silly("This is a silly message.");

NDJson Logging

When NDJson logging is enabled, log messages are formatted as newline-delimited JSON. You can retrieve the NDJson formatted log using:

// Enable NDJson logging
Logger.NDJson = true;

// Retrieve NDJson log data
const ndjsonLog = Logger.getNDJson();
console.log(ndjsonLog);

// Clear NDJson log data
Logger.resetNDJson();

Customization

1. Customizing Log Colors

You can customize the colors associated with different logging levels by modifying the LevelColors mapping:

// Change colors for different log levels
Logger.LevelColors[Logger.Levels.ERROR] = Logger.Colors.BRIGHT_RED;
Logger.LevelColors[Logger.Levels.INFO] = Logger.Colors.GREEN;

2. Customizing Log Message Format

You can also customize the format of the log messages by setting the Logger.format string. This format string can include the following placeholders:

• {date}: Inserts the current timestamp.
• {type}: Inserts the log level type (e.g., ERROR, INFO).
• {message}: Inserts the actual log message.

Example of customizing the log format:

// Set a custom log message format
Logger.format = "[{date}] - {type}: {message}";