Simple Javascript logger for Node.js and Browsers
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README.md

logplease

Simple Javascript logger for Node.js and Browsers

DEMO Open the dev tools to see the log output

Screenshot

logplease does two simple things: output log messages to the console and/or to a file (Node.js only) and display the log messages with nice colors. Inspired by log4js and debug.

Features

  • Log messages to stdout or a file
  • Customize the log messages
  • Log levels
  • Colors!
  • Work in Node.js and Browsers

Install

npm install logplease

Examples

Node.js

npm run example

Browser

Open example/index.html in your browser.

Usage

Node.js / Webpack

See example/example.js for details.

const Logger = require('logplease');
const logger = Logger.create('utils');
logger.debug(`This is a debug message`);
logger.log(`This is a log message`); // alias for debug()
logger.info(`This is a info message`);
logger.warn(`This is a warning`);
logger.error(`This is an error`);

Default log level is DEBUG. You can set the log level with LOG environment variable, eg. LOG=debug node example/example.js. See Log levels for available options.

Browser

Copy dist/logplease.min.js to your javascripts directory and include it in your html. See example/index.html for details.

<body>
  <script type="text/javascript" src="dist/logplease.min.js" charset="utf-8"></script>
  <script type="text/javascript">
    var logger  = Logger.create('logger name');
    logger.debug(`This is a debug message`);
    logger.log(`This is a log message`); // alias for debug()
    logger.info(`This is a info message`);
    logger.warn(`This is a warning`);
    logger.error(`This is an error`);
  </script>
</body>

Options

You can customize your logger to not show the timestamp or the log level, disable colors or specify, if using a log file, to overwrite the log file at start instead of appending to it.

const Logger = require('logplease');
const logger = Logger.create("logger name", options);

Available options and defaults:

const options = {
  useColors: true,     // Enable colors
  color: Colors.White, // Set the color of the logger
  showTimestamp: true, // Display timestamp in the log message
  showLevel: true,     // Display log level in the log message
  filename: null,      // Set file path to log to a file
  appendFile: true,    // Append logfile instead of overwriting
};

Log levels

DEBUG
INFO
WARN
ERROR
NONE

Default log level is DEBUG. To display errors only, use ERROR. To turn off all logging, use NONE.

Global log level

You can set a global log level to display only the wanted log messages.

const Logger = require('logplease');
Logger.setLogLevel(Logger.LogLevels.ERROR) // Show only ERROR messages
// or
Logger.setLogLevel('ERROR')

You can mute all loggers with log level NONE:

Logger.setLogLevel(Logger.LogLevels.NONE) // output nothing

Global log file

You can set a global log file to which all loggers write to.

const Logger = require('logplease');
const logger1 = Logger.create("logger1");
const logger2 = Logger.create("logger2");
Logger.setLogfile('debug.log');
logger1.debug('hello world 1');
logger2.debug('hello world 2');
// ==> 'debug.log' contains both log messages

Log file

You can set a log file per logger.

const Logger = require('logplease');
const logger1 = Logger.create("logger1", { filename: 'debug.log' });
const logger2 = Logger.create("logger2");
logger1.debug('hello world 1'); // writes to 'debug.log'
logger2.debug('hello world 2'); // doesn't write to 'debug.log'

Colors

You can set a color per logger. Default color in Node.js is White and in the browser Black.

const Logger = require('logplease');
const logger = Logger.create("logger name", { color: Logger.Colors.Yellow });

Colors:

Black, Red, Green, Yellow, Blue, Magenta, Cyan, Grey, White

Tests

Run tests with:

npm test

Build

Install build dependencies:

npm install

Build the browser distributable and examples:

npm run build

Build the browser distributable only:

npm run build:dist

The distributable file will be located in dist/logplease.min.js

Build the browser example:

npm run build:examples