Logger

Logger is a Node.js package for logging information with various formatting options. The package provides a simple interface to create a logger with different log levels like debug, info, success, warning, and error. Each level has a specific color and symbol to visually differentiate them. The logger can write to files, streams, or an array of files and streams.

Installation

You can install Logger via NPM by running the following command

1npm i @nandn/logger --save-dev

Installation

You can install Logger via NPM by running the following command

1npm i @nandn/logger --save-dev

Usage

The Logger package exports a createLogger function that you can use to create a new logger instance. The createLogger function takes two optional arguments:

• output (type: $Loggable | iLoggerOutputs): This argument specifies where the logs will be written. It can be a stream, file, array of streams or files, or an object that maps log types to streams or files.
• options (type: iLoggerOptions): This argument specifies various formatting options for the logger.

Example - STDOUT

1import { createLogger } from '@nandn/logger'; // const { createLogger } = require('@nandn/logger') // for CommonJS system
2
3// Create a logger instance that logs to the console
4const Log = createLogger();
5
6// Log some information
7Log('Hello, world!'); // outputs "Hello, world!"
8
9// Log some success information
10Log.success('Operation succeeded!'); // outputs "✅ Operation succeeded!" (will be in green color once logged in terminal)
11
12// Log some debug information
13Log.debug('Some debug info'); // outputs "🐞 Some debug info" (will be in purple color once logged in terminal)

Example - FILES

1import { createLogger } from '@nandn/logger'; // const { createLogger } = require('@nandn/logger') // for CommonJS system
2import path from 'path'; // const path = require('path') // for CommonJS system
3
4const Log = createLogger(
5  {
6    success: {
7      type: 'FILE',
8      path: path.join(__dirname, './logs/success-logs.log'),
9    },
10    error: {
11      type: 'FILE',
12      path: path.join(__dirname, './logs/error-logs.log'),
13      options: {
14        // the following options applies to only this perticular output and will take precedence over general options
15        showTime: false, // showTime will be false for this output whereas it  will stay true for the rest of the outputs as it is true in general options
16        showSymbol: false,
17      },
18    },
19  },
20  {
21    // general options (applies to all the outputs)
22    showTime: true,
23  }
24);
25
26// Log a success message
27Log.success('This is a success log'); // [Logger] [Wed Apr 12 2023] ✅ This is a success log // This will be logged to `./logs/success-logs.log`
28
29// Log a failure message
30Log.error('This is an error log'); // [Logger] This is an error log // this will be logged to `./logs/error-logs.log`
31
32// Export the logger instance to make it available for the whole project
33export default Log; // module.exports = Log // for CommonJS system

Example - BOTH and Periodic File logging

1import { createLogger } from '@nandn/logger'; // const { createLogger } = require('@nandn/logger') // for CommonJS system
2import path from 'path'; // const path = require('path') // for CommonJS system
3
4const Log = createLogger({
5  // Pass an array to specify multiple outputs
6  success: [
7    process.stdout, // You can also use 'console' as a short hand to process.stdout
8    { type: 'FILE', path: path.join(__dirname, './logs/success-logs-1.log') },
9    { type: 'FILE', path: path.join(__dirname, './logs/success-logs-2.log') }, // You can pass as many outputs as you want
10  ],
11  error: [
12    { type: 'STD_OUT', target: process.stdout, options: { colorize: false } }, // If you want to pass options to an STDOUT, you have to use the STD_OUT type
13    {
14      type: 'FILE',
15      path: path.join(__dirname, './logs/error-logs'),
16      options: {
17        periodic: true, // If periodic is set to true, the logger will create a new file every `period`
18        period: '10 min', // The period can be specified in days, hours, minutes ('1d', '2h', '30m', '4 days', '13 hrs', '2 minutes', '1hr 4min', '1d 2h 30m', etc. are all valid periods)
19        // period: 3600000, // You can also pass the period in milliseconds (in this case you have to pass period as a number instead of a string)
20      },
21    },
22  ],
23});
24
25// Log a success message
26Log.success('This is a success log');
27/*
28[Logger] ✅ This is a success log                     // This will be logged to STDOUT in green color
29[Logger] [Wed Apr 12 2023] ✅ This is a success log   // This will be logged to `./logs/success-logs-1.log`
30[Logger] [Wed Apr 12 2023] ✅ This is a success log   // This will be logged to `./logs/success-logs-2.log`
31*/
32
33// Log a failure message
34Log.error('This is an error log');
35/*
36[Logger] ❌ This is an error log                      // This will be logged to STDOUT without any color (as colorize is set to false for this perticular output)
37[ERROR] [Wed Apr 12 2023] This is an error log        // this will be logged to `./logs/error-logs/12-4-2023 23.40.00 - 12-4-2023 23.50.00.log`
38
39Every thing logged in between '12-4-2023 23.40.00' and '12-4-2023 23.50.00' will be logged to the same file
40If you try to log something just after that period, a new file will be created, which will be named as '12-4-2023 23.50.00 - 13-4-2023 00.00.00.log'
41If you don't log anything for let's say 3 hrs, no files will be created in that time period
42*/
43// Export the logger instance to make it available for the whole project
44export default Log; // module.exports = Log // for CommonJS system

Options

Option	Type	Default	Description
loggerName	string	'Logger'	The name of the logger. This is used to prefix the log messages.
processArgs	boolean	false	Whether to process the arguments passed to the logger. If set to true, the logger will process the arguments passed to it and format them accordingly.
argsProcessor	function	JSON.stringify	A function that processes the arguments passed to the logger. This function is called only if processArgs is set to true.
newLine	boolean	true	Whether to add a new line after each log message.
lineEnding	string	'\n'	The line ending to use.
showSymbol	boolean	true	Whether to show the log symbol.
spaceAfterSymbol	boolean	true	Whether to add a space after the log symbol.
showName	boolean	true	Whether to show the logger name.
useBracketsForName	boolean	true	Whether to use brackets to enclose the logger name.
nameFormatter	function	name => name	A function that formats the logger name.
symbols	object	{}	An object that maps log types to symbols.

Advanced Usage

Click here for more details.

License

This project is licensed under the MIT License - see the LICENSE file for details