@protorians/logger

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A minimal, typed logger for Node.js and ESM with timestamp formatting, colored levels, prefixes, and integration with @protorians/events-bus.

• Runtime: Node >= 22
• Exports: ESM and CJS (types included)
• Dependencies: @protorians/core, @protorians/events-bus

Table of Contents

• Installation
• Overview
• Quick start
• API
  • Types
  • Class: Logger
  • Example with an instance
  • Disable colors or timestamp
• Events Bus integration
• Formats and rendering
• Best practices
• License

Installation

• pnpm: pnpm add @protorians/logger
• npm: npm i @protorians/logger
• yarn: yarn add @protorians/logger

Overview

The module exposes a Logger class and convenient static methods per level. Output is colorized when the terminal is a TTY (can be disabled), with timestamp (enabled by default) and optional prefix.

Logs also dispatch @protorians/events-bus events for advanced observability.

Quick start

• ESM: import { Logger } from "@protorians/logger"; Logger.info("Starting up"); Logger.warn("Missing config: %s", "PORT"); Logger.error("Failure: %o", new Error("boom"));

• CJS: const { Logger } = require("@protorians/logger"); Logger.debug("Hello");

API

Types

Properties (ILoggerOptions):

Enums from @protorians/core:

Class: Logger

• constructor(options: ILoggerOptions)

  • Creates an instance with options. The instance method print will use options.level (INFO by default) to choose the color and the appropriate console stream.

• print(message: string, ...args: any[]) => void

  • Builds the header (timestamp, level label, prefix) then delegates to the proper console stream:
    • consoleForLevel(level) from @protorians/core (e.g., console.error for ERROR, etc.)
  • Respects:
    • isColorEnabled (auto: process.stdout.isTTY if available)
    • timestamp (true by default)
    • timestampFormat (default HH_MM_SS)
    • prefix + prefixSeparator
  • Emits an event via @protorians/events-bus (see below).

• Convenience static methods (each creates a Logger with defaults, sets the level, and calls print):

Defaults used by these static helpers:

Example with an instance

import { Logger } from "@protorians/logger"; import { LevelEnum, TimestampEnum } from "@protorians/core";

const appLogger = new Logger({ prefix: "api", level: LevelEnum.INFO, // level used by print timestamp: true, timestampFormat: TimestampEnum.HH_MM_SS, prefixSeparator: " | ", isColorEnabled: true });

appLogger.print("Server ready at %s", "http://localhost:3000");

// Change level dynamically (instance): appLogger.options.level = LevelEnum.DEBUG; appLogger.print("Request: %o", { method: "GET", path: "/" });

Disable colors or timestamp

Logger.info("Colors auto based on TTY"); new Logger({ level: LevelEnum.INFO, isColorEnabled: false }).print("No color"); new Logger({ level: LevelEnum.INFO, timestamp: false }).print("No timestamp");

Events Bus integration

Every log emits an event via EventBus.dispatch(key, payload) where payload is:

• { message: string, level: LevelEnum, header: string, args: any[] }

The key depends on the level:

This lets you centralize or redirect logs to other targets (file, telemetry, etc.) by subscribing to the @protorians/events-bus package event bus.

Formats and rendering

• The level label is uppercased (e.g., INFO, ERROR). For LevelEnum.NORMAL, the label shown is "LOG".
• The timestamp is rendered in brackets: [HH:MM:SS] by default.
• Colors come from consoleColorizeLevel in @protorians/core.

Best practices

• Use the static methods for quick logs.
• Create Logger instances if you need a dedicated prefix (e.g., a microservice), a specific format, or to lock a level.
• Set isColorEnabled to false for non-TTY CI environments if needed.

License

ISC