A simple Logger helper for nodejs

micro-logger is a straightforward, zero dependencies library for logging. It logs to a single predefined file. When an option {tee: true} is given, micro-logger shows colored messages in the console. If a log file is not defined, micro-logger writes to the console only.

Homepage: https://github.com/popovmp/micro-logger

Synopsis

// Intialize `micro-logger`in your index.js
const logger = require("@popovmp/micro-logger").init("./logs/log.txt");
logger.info("App started", "app::index");

// Use it in your other files
const logger = require("@popovmp/micro-logger");
logger.info("Hello World!", "app::sayHello");

// Alternative use
const {logInfo, logError, logText, logDebug, logSuccess} = require("@popovmp/micro-logger");
logInfo("Mamma mia!");

Installation

npm install @popovmp/micro-logger

Usage

micro-logger must be initialized with the path to the log file in order to write the log. It is a good idea to set the path relative to __dirname.

If you don't want the logger to write to a file, you may skip the init part or to call it without args. The logger will only show the messages in the terminal in that case.

If micro-logger is not initialized, it writes to the console. It allows it to be used in modules without initialization.

You have to initialize the logger only once. It is best to do it in the application main script index.js or app.js.

micro-logger writes to the log file asynchronously (aka Fire and Forget). You can log only a message, or a message and sender. Sender can be a method name or other hint.

There are three log methods: logger.info, logger.error, and logger.text.

The methods logger.info, logger.error logs:

• a date and time in [yyyy-dd-MM hh:mm:ss] format
• tag [INFO] or [ERROR]. the tags help to search the log file or grep it by a tag.
• sender (optional) in [sender] format (if provided).

The logger.text method logs only the provided message. It doesn't log a date, a label or a sender.

const path = require("path");
const {
 logInfo, logText, logError, logDebug, logSuccess, getLastError,
} = require("@popovmp/micro-logger").init( path.join(__dirname, "logs/log.txt"), {tee: true, suppress: ["debug"]} );

logInfo("Hello, World!");                          // => 2020-08-21 06:21:11 [INFO] Hello, World!
logInfo("GET index", "app::router");               // => 2020-08-21 06:21:11 [INFO] [app::router] GET index
logError("Ohh!", "bank::delete-account");          // => 2020-08-21 06:21:11 [ERROR] [bank::delete-account] Ohh!
logText("So Long, and Thanks for All the Fish!");  // => So Long, and Thanks for All the Fish!

Last error

micro-logger has two methods for getting and resetting the last logged error message: getLastError and resetLastError.

getLastError returns the last logged error message by the logError or logger.error methods.

You can reset the last error with the resetLastError method. When resetLastError is called without parameters, it sets the last error to undefined. resetLastError can be called with null to set the last error to null.

getLastError();         // undefined
logError("some eror");
getLastError();         // some error
resetLastError();
getLastError();         // undefined

Options

The init method accepts an options options parameter. It has two property tee: boolean and suppress: string[].

When tee is set to true, the logger doubles the message on the console.

The suppress parameter accepts a string[]. It suppresses the logging of the tags included.

The possible values are:

{
 "suppress": ["debug", "text", "info", "error", "success"]
}

The default values of suppress is an empty list.

const path   = require("path");
const logger = require("@popovmp/micro-logger");
logger.init(path.join(__dirname, "logs/log.txt"), {tee: true});

logger.info("Foo"); // Logs 'Foo', Prints 'Foo' on the console.

Methods

micro-logger exports the following methods:

/**
 * Sets the log path
 * @function init
 *
 * @param {string} logFilePath
 * @param {LoggerOptions} [options]
 *
 * @returns { {init, error, info, text} }
 */
logger.init(logFilePath, options);

/**
 * Logs a debug message to a log file
 *
 * @param {Error|object|string} message
 * @param {string} [sender]
 */
logDebug(message, sender);

/**
 * Logs a message to a log file
 *
 * @param {Error|object|string} message
 * @param {string} [sender]
 */
logInfo(message, sender);

/**
 * Logs an error to a log file
 *
 * @param {Error|object|string} message
 * @param {string} [sender]
 */
logEror(message, sender);

/**
 * Logs a success information to a log file
 *
 * @param {object|string} message
 * @param {string} [sender]
 */
logSuccess(message, sender);

/**
 * Logs an error to a log file
 *
 * @param { string } message
 */
logText(message);

/**
 * Logs a debug message to a log file
 *
 * @param {Error|object|string} message
 * @param {string} [sender]
 */
logger.debug(message, sender);

/**
 * Logs a message to a log file
 *
 * @param {Error|object|string} message
 * @param {string} [sender]
 */
logger.info(message, sender);

/**
 * Logs an error to a log file
 *
 * @param {Error|object|string} message
 * @param {string} [sender]
 */
logger.error(message, sender);

/**
 * Logs a success information to a log file
 *
 * @param {object|string} message
 * @param {string} [sender]
 */
logger.success(message, sender);

/**
 * Logs an error to a log file
 *
 * @param { string } message
 */
logger.text(message);

License

micro-logger is free for use and modification. No responsibilities for damages of any kind.

Copyright (c) 2020 Miroslav Popov