@rmtc/logger

Consistent logging for the @rmtc/toolchain CLI.

[!WARNING] This package is intended for internal use by @rmtc/toolchain. It's probably not useful by itself.

[!WARNING] This project is intended for use in @rowanmanning's projects. It's free to use but I don't offer support for use-cases outside of what I need.

Table of Contents

• Requirements
• Usage
  • Logging
  • Configuration
    • logLevel
    • prefix
  • Child loggers
• Contributing
• License

Requirements

This library requires the following to run:

• Node.js 18+

Usage

Install the module with npm:

npm install @rmtc/logger

This module exports a Logger class which is used to provide consistent logging for the command line interfaces:

const {Logger} = require('@rmtc/logger');
const logger = new Logger();
logger.info('Hello World!');

Logging

The logger has different log methods depending on the level of log you want to output:

logger.debug('This is a debug-level message');
logger.info('This is an info-level message');
logger.warn('This is a warning message');
logger.error('This is an error message');

The error method can also accept an Error object, which it will render neatly:

logger.error(new Error('something went wrong));

Configuration

When you create a logger, you can configure it with the following options by passing them as part of an options object:

const logger = new Logger({
    // options go here
});

The available options are:

logLevel

String. The lowest log level to output logs for. Any less important log than this level will not be output. Defaults to process.env.LOG_LEVEL, and if that's not set then info. E.g.

const logger = new Logger({ logLevel: 'warn' });
logger.info('shh'); // Logs nothing

prefix

String. A string to prepend to all log messages from the logger. A space will be added to separate the prefix from the message. Defaults to an empty string. E.g.

const logger = new Logger({ prefix: 'Hello' });
logger.info('World!'); // Logs "Hello World!"

Child loggers

If you want to chain prefixes together, you can create child loggers. These inherit the settings from their parent but you can add a further prefix. E.g.

const logger = new Logger({ prefix: 'one' });
logger.info('testing'); // Logs "one testing"

const childLogger = logger.child({ prefix: 'two' });
logger.info('testing'); // Logs "one two testing"

Contributing

See the central README for a contribution guide and code of conduct.

License

Licensed under the MIT license. Copyright © 2023, Rowan Manning