JsLog

JsLog (pronounced /ˈdʒəslɒɡ/), from "Just Log", is a simple, lightweight, and pluggable logger for JavaScript and TypeScript.

!TypeScript

Features

- Simple and lightweight: No dependencies and a small footprint.
- Pluggable: Extend the logger's functionality with plugins.
- Multiple log levels: Supports trace, debug, info, log, warn, and error.
- TypeScript support: Written in TypeScript and includes type definitions.

Installation

``bash
npm install @geezgus/jslog
`

Usage

`typescript
import { logger } from 'jslog';

logger.info('Hello, world!');
// Output: Hello, world!

logger.error('This is an error message.');
// Output: This is an error message.
`

$3

JsLog's functionality can be extended with plugins. Here's an example of how to use the timestamp and levelFilter plugins:

`typescript
import { logger as baseLogger } from 'jslog';
import { levelFilter, LogLevel, timestamp } from 'jslog/plugins';

const logger = baseLogger
.use(timestamp('utc'))
.use(levelFilter(LogLevel.Info));

logger.info('This message has a timestamp.');
// Output: [Thu, 03 Jul 2025 12:00:00 GMT] This message has a timestamp.

logger.debug('This message will be filtered out.');
// Output:
`

Plugins

JsLog's core is small and simple. All additional features are implemented as plugins.

$3

- levelFilter: Filters log messages based on their severity level.
- timestamp: Adds a timestamp to the beginning of the log message.

$3

A plugin is just a function that receives the logger's context as an argument. The context contains the log method (e.g., info, error) and the arguments passed to it.

Here's an example of a plugin that adds a prefix to all log messages:

`typescript
import { LoggerContext } from 'jslog';

const prefix = (text: string) => (ctx: LoggerContext) => {
ctx.args.unshift(text);
};

const logger = baseLogger.use(prefix('[API]'));

logger.info('This is a message from the API.');
// Output: [API] This is a message from the API.
`

Development

$3

- npm run build: Builds the project.
- npm run dev: Runs the project in development mode.
- npm run lint: Lints the source code.
- npm run format`: Formats the source code.

License

This project is licensed under the MIT License.