Logsen

The only logger you will ever need in NodeJS.

Installation

Just install it like any other package from npm.

$ npm i logsen

You don't need to install typings for it, they ship with the regular installation.

Usage

JavaScript

You can just require it like any other JS-module.

const $ = require("logsen");

If you want to import the ExpressUtils aswell, use the destructor-import:

const { $, ExpressUtils } = require("logsen");

TypeScript

You can just import it like a regular TS-module.

import $ from "logsen";

If you want to import the ExpressUtils aswell, destructor your import:

import { $, ExpressUtils } from "logsen";

Functionality

Patterns

You can use a custom pattern for logged messages. If you don't want create your own format, a default format is automatically used.

Logsen supports the following placeholders for formatting the date:

• DD for days
• MM for months
• YY and YYYY for years
• hh for hours
• mm for minutes
• ss for seconds

You can change the pattern for the root logger whenever you want:

$.config.formatter = new PatternFormatter("DD-hh_MM:mm.YY,ss");

Logging

Logsen's loggers provides you some functions to manage your console-output:

/**
 * Log a custom record to the default backend.
 * It is not styled, just like you would use "console.log(...)".
 */
$.log({
    level: LogLevel.Info,
    timestamp: new Date(),
    message: "..."
});

/**
 * Log something to the default backend, but with a blue "[INFO]" infront of it.
 */
$.info("...");

/**
 * Log something to the default backend, but with a green "[SUCCESS]" infront of it.
 */
$.success("...");

/**
 * Log something to the standard error, but with a red "[ERROR]" infront of it.
 */
$.error("...");

Child Loggers

The default logger in Logsen is called the "root" logger and is exported under the name $. You can, however, create custom loggers that inherit the configuration like this:

const myLogger = $.makeLogger({
    name: "A cool logger",
    level: LogLevel.Error
});

This will automatically copy the configuration and the selected backend from the root logger $ for all unspecified properties.

Of course, you can also create your completely own loggers:

const logger = new Logger({
    name: "My very own logger",
    level: LogLevel.Info,
    formatter: new PatternFormatter()
}, new StdoutBackend());

Note that this will, however, ignore the root logger's configuration and is thus discouraged for libraries.

Custom Backends

Logsen also makes it easy to log to other destinations than stdout. For example, you can easily configure the root logger to output both to stdout and a file:

$.backend = new CombinedBackend([
    new StdoutBackend(),
    new FileBackend("path/to/my/log.txt")
]);

Express

To log incoming requests to your express-application, you can use ExpressUtils.log:

/**
 * Import Express and ExpressUtils.
 */
import express from "express";
import { ExpressUtils } from "logsen";

/**
 * Create express app and use the logging middleware in it.
 */
const app = express();
app.use(ExpressUtils.log);

/**
 * Now every request will be logged like this:
 *
 *      [METHOD] <URL>
 */
...