@asd14/fancy-logger

Fancy console logger for Node.js and browser.

• Runtime-specific entrypoints: @asd14/fancy-logger/node and @asd14/fancy-logger/browser
• Two output formats: colored text for humans, JSON for log pipelines
• Level gating: error, warning, info, debug
• Variable redaction hook: redact variables before they leave your process
• Node.js extras: animated spinner and tadaa banner

• Install
• Use cases
  • Node logs
  • Long-running tasks (spinner)
  • Browser logs
• API
  • buildLogger
    • Parameters
    • Returns
• Develop
• Changelog

Install

# Node apps (with spinner)
npm install @asd14/fancy-logger yocto-spinner

# Frontend apps
npm install @asd14/fancy-logger

Node runtime requirement: >=22.12.0.

[!NOTE]
yocto-spinner is an optional peer dependency used only by @asd14/fancy-logger/node for logger.spinner.

Use cases

Node logs

import { buildLogger } from "@asd14/fancy-logger/node"

const logger = buildLogger({
  namespace: "api",
  level: process.env["LOG_LEVEL"] === "debug" ? "debug" : "info",
  format: process.env["LOG_FORMAT"] === "json" ? "json" : "text",
  output: "stderr",
})

logger.info("Request received", { method: "GET", path: "/users" })
logger.error("Request failed", { status: 500, reason: "timeout" })

Long-running tasks (spinner)

import { buildLogger } from "@asd14/fancy-logger/node"

const logger = buildLogger({ namespace: "sync", level: "info" })

const task = logger.spinner.start("Sync users", { batch: 1 }, { total: 3 })

task.tick({ id: "user-1" })
task.tick({ id: "user-2" })
task.stop("done")

logger.tadaa({
  title: "Sync complete",
  message: "3 users synced",
  note: "No retries",
})

Browser logs

import { buildLogger } from "@asd14/fancy-logger/browser"

const logger = buildLogger({ namespace: "web/app", level: "info" })

logger.info("Loaded", { route: "/home" })
logger.tadaa({ title: "Session ready", message: "MCP connected" })

API

buildLogger

Import buildLogger from the runtime you need:

import { buildLogger } from "@asd14/fancy-logger/node"
// or
import { buildLogger } from "@asd14/fancy-logger/browser"

• Node entrypoint: build a Node logger with text or JSON output, a tadaa banner, and a spinner.
• Browser entrypoint: build a browser logger with text or JSON output.

Parameters

| Name | Type | Required | Default (node) | Default (browser) | | ------------ | ----------------------------------------------------------------------- | -------- | ------------------------------------- | ----------------- | | namespace | string | yes | - | - | | level | "error" \| "warning" \| "info" \| "debug" | no | process.env["LOG_LEVEL"] ?? "info" | "info" | | format | "text" \| "json" | no | process.env["LOG_FORMAT"] ?? "text" | "text" | | output | "stderr" \| "stdout" | no | "stderr" | "stdout" | | redactor | (input: Record<PropertyKey, unknown>) => Record<PropertyKey, unknown> | no | undefined | undefined | | thresholds | { good: number; meh: number } | no | { good: 100, meh: 500 } | - |

Returns

• error(message, variables?)
• warn(message, variables?)
• info(message, variables?)
• success(message, variables?)
• debug(message, variables?)
• tadaa({ title, message?, note? })

Only on logger built from @asd14/fancy-logger/node:

• spinner
  • start(message, variables?, { total? }), returns a handle with:
    • tick(variables?)
    • stop(message, variables?)
    • stopError(message, variables?)
    • stopWarn(message, variables?)

Develop

npm run lint
npm run typecheck
npm run unit-test
npm run build

Changelog

See releases.