Node.js Logger

Already-configured logger for Node.js applications based on Winston.

Table of contents (click to open)

• The Reason
• Requirements
  • For Development
• Usage
• Configuration
  • Configuring Global Log Level
  • Setting Custom Log Level per Logger After Setting Up Global Log Level
  • Using Custom Built-In Logging Levels
  • Adding File Logging

The Reason

It is really annoying to set up logging for every new Node.js project that doesn't use any framework with its built-in logger (e.g., Nest.js).

This package provides a ready-to-use logger based on Winston, configured to log messages to the console in a consistent format similar to Nest.js' logger (YYYY-MM-DD HH:mm:ss LEVEL [context] message).

Warning

This project only supports console logging. If you need file logging, please refer to adding file logging.

Requirements

• Node.js - Version 22.18.0 or higher
• Winston - Version 3.18.3 or higher

For Development

• EditorConfig - Code style consistency across editors and IDEs
• ESLint - Linting utility for JavaScript and TypeScript
• PNPM - Fast, disk space efficient package manager
• Prettier - Code formatter

Usage

1. Install the Node.js Logger and Winston packages:

   # Using NPM
   npm install @jscv-solutions/node-logger winston
   
   # Using Yarn
   yarn add @jscv-solutions/node-logger winston
   
   # Using PNPM
   pnpm install @jscv-solutions/node-logger winston

2. Import the ConsoleLogger class and use its getLogger() method in your Node.js application:

   // Using CommonJS
   const ConsoleLogger = require('@jscv-solutions/node-logger');
   const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>', '<LOG_LEVEL>');

   // Using ES Modules
   import ConsoleLogger from '@jscv-solutions/node-logger';
   const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>', '<LOG_LEVEL>');

   Note: Replace <COMPONENT_NAME> with the name of your component (e.g., 'MyApp'), and <LOG_LEVEL> with the desired log level (e.g., 'info', 'debug', 'error').

3. Use the logger in your application:

   logger.info('This is an info message'); // YYYY-MM-DD HH:mm:ss     INFO [context] This is an info message
   logger.debug('This is a debug message'); // YYYY-MM-DD HH:mm:ss     DEBUG [context] This is a debug message
   logger.error('This is an error message'); // YYYY-MM-DD HH:mm:ss     ERROR [context] This is an error message

Configuration

Configuring Global Log Level

You can configure the global log level for all loggers by setting the LOGGING_LEVEL environment variable before starting your Node.js application:

export LOGGING_LEVEL='<LOG_LEVEL>'
node your-app.js

Replace <LOG_LEVEL> with the desired log level (e.g., 'info', 'debug', 'error').

Then, you can get loggers without specifying the log level explicitly:

// Using CommonJS
const ConsoleLogger = require('@jscv-solutions/node-logger');
const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>');

// Using ES Modules
import ConsoleLogger from '@jscv-solutions/node-logger';
const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>');

Setting Custom Log Level per Logger After Setting Up Global Log Level

If you want to set a custom log level for a specific logger after configuring the global log level, you can do so as follows:

// Using CommonJS
const ConsoleLogger = require('@jscv-solutions/node-logger');
const { transports } = require('winston');

const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>');

logger.level = '<CUSTOM_LOG_LEVEL>';

// Using ES Modules
import ConsoleLogger from '@jscv-solutions/node-logger';
import { transports } from 'winston';

const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>');

logger.level = '<CUSTOM_LOG_LEVEL>';

Using Custom Built-In Logging Levels

This package includes a custom set of levels out of the box. Why? Because verbose-related logs should be visible (even if debug logs should not appear).

This is what the custom set of levels looks like:

const customLogLevels = {
    colors: {
        error: 'red',
        warn: 'yellow',
        help: 'cyan',
        data: 'grey',
        info: 'green',
        verbose: 'cyan',
        debug: 'blue',
        prompt: 'grey',
        input: 'grey',
        silly: 'magenta'
    },
    levels: {
        error: 0,
        warn: 1,
        help: 2,
        data: 3,
        info: 4,
        verbose: 5,
        debug: 6,
        prompt: 7,
        input: 8,
        silly: 9
    }
};

The only difference from the set of logging levels from Winston is the severity for the verbose level. Everything else remains to be the same as in Winston (even the colors).

Note: The custom built-in logging levels is disabled by default.

For using this custom set of logging levels, you can either set the shouldUseCustomLogLevels parameter from the getLogger() method to true:

// Using CommonJS
const ConsoleLogger = require('@jscv-solutions/node-logger');
const { transports } = require('winston');

const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>', '<LOG_LEVEL>', true);

logger.error('This is an error message'); // YYYY-MM-DD HH:mm:ss     ERROR [context] This is an error message
logger.warn('This is a warning message'); // YYYY-MM-DD HH:mm:ss     WARN [context] This is a warning message
logger.help('This is a help message'); // YYYY-MM-DD HH:mm:ss     HELP [context] This is a help message
logger.data('This is a data message'); // YYYY-MM-DD HH:mm:ss     DATA [context] This is a data message
logger.info('This is an info message'); // YYYY-MM-DD HH:mm:ss     INFO [context] This is an info message
logger.verbose('This is a verbose message'); // YYYY-MM-DD HH:mm:ss     VERBOSE [context] This is a verbose message
logger.debug('This is a debug message that will not appear');

// Using ES Modules
import ConsoleLogger from '@jscv-solutions/node-logger');
import { transports } from 'winston';

const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>', '<LOG_LEVEL>', true);

logger.error('This is an error message'); // YYYY-MM-DD HH:mm:ss     ERROR [context] This is an error message
logger.warn('This is a warning message'); // YYYY-MM-DD HH:mm:ss     WARN [context] This is a warning message
logger.help('This is a help message'); // YYYY-MM-DD HH:mm:ss     HELP [context] This is a help message
logger.data('This is a data message'); // YYYY-MM-DD HH:mm:ss     DATA [context] This is a data message
logger.info('This is an info message'); // YYYY-MM-DD HH:mm:ss     INFO [context] This is an info message
logger.verbose('This is a verbose message'); // YYYY-MM-DD HH:mm:ss     VERBOSE [context] This is a verbose message
logger.debug('This is a debug message that will not appear');

Or you can configure it globally setting the SHOULD_USE_CUSTOM_LOG_LEVELS environment variable to true:

export LOGGING_LEVEL='verbose'
export SHOULD_USE_CUSTOM_LOG_LEVELS='true'
node your-app.js

Then, you can get loggers without specifying the shouldUseCustomLogLevels parameter explicitly:

// Using CommonJS
const ConsoleLogger = require('@jscv-solutions/node-logger');
const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>');

// Using ES Modules
import ConsoleLogger from '@jscv-solutions/node-logger';
const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>');

Adding File Logging

If you want to add file logging to the existing console logger, you can add File transport from Winston as follows:

// Using CommonJS
const ConsoleLogger = require('@jscv-solutions/node-logger');
const { transports } = require('winston');

const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>', '<LOG_LEVEL>');

logger.add(new transports.File({ filename: 'app.log' }));

// Using ES Modules
import ConsoleLogger from '@jscv-solutions/node-logger';
import { transports } from 'winston';

const logger = ConsoleLogger.getLogger('<COMPONENT_NAME>', '<LOG_LEVEL>');

logger.add(new transports.File({ filename: 'app.log' }));