@marceliwac/logger

Logger

Logger is a simple static class utility wrapper that can be used to substitute the default logging behaviour.

It provides methods for info, debug, warn and error outputs, supporting both message and (message, object) payloads, preventing logging of just the objects. This makes the logs more legible and less cryptic.

Installation

The package should be installed as dependency of the project.

npm i --save @marceliwac/logger

Usage

There are four streams of logs that can be accessed using this package: info, debug, warn and error. Only info and error logs will output when the environment is set to either prod or production.

To output the message, simply import the module and access its static methods. For logging objects, use the same methods followed by an object payload. Supplied objects will be stringified and in the cases where circular references are present - substituted with "__cycle__". The stringification is provided by the fast-json-stable-stringify package.

const Logger = require('@marceliwac/logger');

Logger.info('This is a message.');
// "This is a message."

Logger.info('This is a message that has an object payload.', {key: 'value'});
// "This is a message that has an object payload."
// {
//   "key": "value"
// }

Separate methods handle the output to different streams.

const Logger = require('@marceliwac/logger');

// Will print only when NODE_ENV is set to 'prod' or 'production'. 
Logger.info('This is an info message.');
Logger.error('This is an error message.');

// Will print regardless of the set environment. 
Logger.debug('This is an info message.');
Logger.warn('This is an error message.');

To enforce the clarity and structure within logs, in the cases when supplied message is not a string or an empty string, the logging error message will be displayed. Errors will not be thrown to prevent accidental application from breaking and supplied values will be logged regardless of malformation. This is to allow the users to see why they made an error and enable debugging while still enforcing the log structure. Examples that would trigger this behaviour include:

const Logger = require('@marceliwac/logger');

Logger.info();
// Logger method supplied with malformed input! Valid input requires non-empty (string) message with
//      an optional (object) object. Supplied values: 
// {}

Logger.debug({key: 'value'});
// Logger method supplied with malformed input! Valid input requires non-empty (string) message with
//      an optional (object) object. Supplied values: 
// {
//   "message": {
//     "key": "value"
//   }
// }

Logger.warn('');
// Logger method supplied with malformed input! Valid input requires non-empty (string) message with
//      an optional (object) object. Supplied values: 
// {
//   "message": ""
// }

Logger.error(null, {key: 'value'});
// Logger method supplied with malformed input! Valid input requires non-empty (string) message with
//      an optional (object) object. Supplied values: 
// {
//   "message": null,
//   "object": {
//     "key": "value"
//   }
// }

Error Logging

In addition to the above, in the cases where the supplied object is of Error type (as checked by the isError method) the logger will not attempt to directly stringify it. Rather, the serialize-error module will be used to serialize the contents of the object.

Future work

Several improvements could be made to the software. Primarily, the current version could be extended to support both RequireJS and ES6-modules. Following is a non-exhaustive list of features planned for development:

• [ ] Add support for both RequireJS and ES6-module imports.
• [ ] Add CI/CD.

Contributing

If you are interested in the further development of the module, feel free to submit an issue via GitLab Issues. It will be used both for bug tracking and feature development.