Better console log formatter for Winston

README.md

About

This is a logrus-like improved CLI formatter for Winston.

Formatter supports labels and errors prerry print (from error field).

Output example

formatter.js

'use strict';
const winston = require('winston');
const colors = require('colors/safe');
const { format } = require('date-fns');

const formatLabel = ({label, ...entries}) => ({
    ...entries,
    label: label ? colors.dim(`[${label}]`.toUpperCase()) : null
}) 

const formatLogLevel = level => {
    let lvlString = level;
    let colorFunc = colors.gray;

    switch (level) {
        case "info":
            lvlString = "inf";
            colorFunc = colors.green;
            break;
        case "warn":
            lvlString = "wrn";
            colorFunc = colors.yellow;
            break;
        case "error":
            lvlString = "err";
            colorFunc = colors.red;
            break;
        case "debug":
            lvlString = "dbg";
            break;
        default:
            break;
    }

    return colorFunc(lvlString.toUpperCase());
}

const formatLogEntries = entries => {
    let keys = Object.keys(entries);
    if (!keys.length) {
        return null;
    }

    return Object.entries(entries)
        .filter(([k]) => k !== 'label')
        .map(([k, v]) => {
            if (k === "error") {
                return colors.red(`${k}=${JSON.stringify(v.toString())}`)
            }

            return `${colors.cyan(k + '=')}${JSON.stringify(v)}`
        }).join(' ')
}

const logFormatters = [
    winston.format.timestamp({
        format: format(new Date(), 'HH:mm:ss')
    }),
    winston.format(formatLabel)(),
    winston.format(({level, timestamp, message, ...msg}) => ({
        ...msg,
        level: formatLogLevel(level),
        timestamp: colors.gray(timestamp),
        message: level === 'error' ? colors.red(message) : message
    }))(),
    winston.format.printf(
        ({label, timestamp, level, message, ...rest}) => (
            [timestamp, label, level, message, formatLogEntries(rest)].filter(v => !!v).join(' ')
        )
    )
];

const defaultOpts = {
    transports: new winston.transports.Console({
        format: winston.format.combine(...logFormatters)
    })
};

const newLogger = level => winston.createLogger({
    ...defaultOpts,
    level
});

exports.newLogger = newLogger;