pretty-js-log/src/log.js

A light logging package for Node.js and Bun applications. Features file logging and beautiful console output.

const fs = require('node:fs')

const tzOffset = (new Date()).getTimezoneOffset() * 60000

const COLORS = Object.freeze({
    reset: '\u001b[0m',
    gray: '\u001b[90m',
    red: '\u001b[31m',
    green: '\u001b[32m',
    yellow: '\u001b[33m',
    blue: '\u001b[34m',
    magenta: '\u001b[35m',
    cyan: '\u001b[36m',
    white: '\u001b[37m',
})

const LEVELS = Object.freeze({
    default: {
        id: COLORS.blue,
        datetime: COLORS.green,
        message: COLORS.white,
        level: COLORS.white
    },
    info: {
        id: COLORS.blue,
        datetime: COLORS.white,
        message: COLORS.blue,
        level: COLORS.blue
    },
    warn: {
        id: COLORS.blue,
        datetime: COLORS.white,
        message: COLORS.yellow,
        level: COLORS.yellow
    },
    error: {
        id: COLORS.blue,
        datetime: COLORS.red,
        message: COLORS.red,
        level: COLORS.red
    },
    debug: {
        id: COLORS.blue,
        datetime: COLORS.green,
        message: COLORS.white,
        level: COLORS.magenta
    }
})

function formatArgs(args) {
    return args
        .map(arg => {
            if (typeof arg === 'object') {
                return JSON.stringify(arg, null, 2)
            }
            return String(arg)
        })
        .join(' ')
}

function messageFactory({ id = '', level, args = [], colors }) {
    const timestamp = (new Date(Date.now() - tzOffset)).toISOString().replace("T", " ").replace('Z', '')
    let message =  `${COLORS.reset}${colors?.datetime}[${timestamp}]${COLORS.reset}`
    
    if (id) {
        message += `${COLORS.reset} - ${colors?.id}[id:${id}]${COLORS.reset}`
    }
    
    if (level) {
        message += `${COLORS.reset} - ${colors?.level}[${level.length === 4 ? level + ' ' : level}]${COLORS.reset}`
    }
    message += `${COLORS.reset} - ${colors?.message}${formatArgs(args)}${COLORS.reset}`
    
    return message
}

function stripAnsiCodes(text) {
    return text.replace(/\u001b\[\d{1,2}m|\u001b\[0m/g, '')
}

function writeToStdout(message) {
    console.log(message)
}

function writeToFile(message, path) {
    fs.appendFileSync(path, stripAnsiCodes(message) + '\n', "utf8")
}

function logFactory({ id, path, colors, toStdout = true }) {
    let currentId = id

    const createLogHandler = (colors, level) => (...args) => {
        const message = messageFactory({
            id: currentId || false,
            colors,
            level,
            args
        })
        if (toStdout !== false) {
            writeToStdout(message)
        }
        if (path) {
            writeToFile(message, path)
        }
    }

    const logger = createLogHandler(colors || LEVELS['default'])
    
    Object.keys(LEVELS)
        .filter(level => level !== 'default')
        .forEach(level => {
            logger[level] = createLogHandler(LEVELS[level], level)
        })

    logger.id = (newId) => {
        currentId = newId
        return logger;
    }

    return logger
}

module.exports = { logFactory }