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

npm i @nandn/logger --save-dev

Installation

You can install Logger via NPM by running the following command

npm 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

import { createLogger } from '@nandn/logger'; // const { createLogger } = require('@nandn/logger') // for CommonJS system

// Create a logger instance that logs to the console
const Log = createLogger();

// Log some information
Log('Hello, world!'); // outputs "Hello, world!"

// Log some success information
Log.success('Operation succeeded!'); // outputs "✅ Operation succeeded!" (will be in green color once logged in terminal)

// Log some debug information
Log.debug('Some debug info'); // outputs "🐞 Some debug info" (will be in purple color once logged in terminal)

Example - FILES

import { createLogger } from '@nandn/logger'; // const { createLogger } = require('@nandn/logger') // for CommonJS system
import path from 'path'; // const path = require('path') // for CommonJS system

const Log = createLogger(
  {
    success: {
      type: 'FILE',
      path: path.join(__dirname, './logs/success-logs.log'),
    },
    error: {
      type: 'FILE',
      path: path.join(__dirname, './logs/error-logs.log'),
      options: {
        // the following options applies to only this perticular output and will take precedence over general options
        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
        showSymbol: false,
      },
    },
  },
  {
    // general options (applies to all the outputs)
    showTime: true,
  }
);

// Log a success message
Log.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`

// Log a failure message
Log.error('This is an error log'); // [Logger] This is an error log // this will be logged to `./logs/error-logs.log`

// Export the logger instance to make it available for the whole project
export default Log; // module.exports = Log // for CommonJS system

Example - BOTH and Periodic File logging

import { createLogger } from '@nandn/logger'; // const { createLogger } = require('@nandn/logger') // for CommonJS system
import path from 'path'; // const path = require('path') // for CommonJS system

const Log = createLogger({
  // Pass an array to specify multiple outputs
  success: [
    process.stdout, // You can also use 'console' as a short hand to process.stdout
    { type: 'FILE', path: path.join(__dirname, './logs/success-logs-1.log') },
    { type: 'FILE', path: path.join(__dirname, './logs/success-logs-2.log') }, // You can pass as many outputs as you want
  ],
  error: [
    { 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
    {
      type: 'FILE',
      path: path.join(__dirname, './logs/error-logs'),
      options: {
        periodic: true, // If periodic is set to true, the logger will create a new file every `period`
        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)
        // 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)
      },
    },
  ],
});

// Log a success message
Log.success('This is a success log');
/*
[Logger] ✅ This is a success log                     // This will be logged to STDOUT in green color
[Logger] [Wed Apr 12 2023] ✅ This is a success log   // This will be logged to `./logs/success-logs-1.log`
[Logger] [Wed Apr 12 2023] ✅ This is a success log   // This will be logged to `./logs/success-logs-2.log`
*/

// Log a failure message
Log.error('This is an error log');
/*
[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)
[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`

Every thing logged in between '12-4-2023 23.40.00' and '12-4-2023 23.50.00' will be logged to the same file
If 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'
If you don't log anything for let's say 3 hrs, no files will be created in that time period
*/
// Export the logger instance to make it available for the whole project
export 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