Module visual-logger

visual-logger

Visual CLI logger for NodeJS

This is a simple logger that combines in-place terminal updates for showing things like progress, spinners, etc.

Demo as used in fyn:

Install

npm install visual-logger

Usage

Log lines scroll normally. Items are the in-place part: each one owns a line at the bottom of the screen that you update as work progresses, and removing it leaves the scrollback clean.

import VisualLogger from "visual-logger";

const logger = new VisualLogger();

logger.info("starting");

logger.addItem({ name: "install", color: "green", display: "Installing", spinner: true });
logger.updateItem("install", "resolving dependencies");
logger.updateItem("install", { msg: "linking", display: "Linking" });
logger.removeItem("install");

logger.info("done");

API

See the full API reference for every option, type, and runtime rule.

Logging

debug(), verbose(), info(), log(), warn(), error() - one per level. Levels are debug (10), verbose (20), info (30), warn (40), error (50), fyi (60) and none (100); each gets its own color, exported as LevelColors.

Messages below the logger's level are saved to logData but not printed. The level defaults to info. Set it with the logLevel constructor option or the logLevel property:

const logger = new VisualLogger({ logLevel: "debug" });
logger.logLevel; // "debug"
logger.logLevel = "warn"; // an unknown name throws TypeError

prefix(str | false) and setPrefix(str) set a prefix on subsequent lines.

Items

method	description
`addItem({ name, color, display, spinner, spinInterval, save })`	add an in-place item; `spinner` may be `true`, a style name or index
`updateItem(name, msg \| { msg, display })`	update what the item shows
`removeItem(name)`	remove it
`clearItems()`	remove all of them
`freezeItems(showItems?)` / `unfreezeItems()`	stop and resume in-place updating - useful around output you don't want overwritten
`setItemType(type)`	`normal`, `simple`, or `none` to turn in-place rendering off (what CI wants)

Item names may be strings or symbols.

Also exported

VisualLogger (also the default export), Levels, LevelColors, LogItemTypes, defaultOutput, and the VisualOutput / OutputInterface types for supplying your own output target.