L4js (Logging For JavaScript) Intro

l4js is a lightweight, user-friendly logging utility designed to simplify the logging process for JavaScript and Node.js applications. Unlike other npm logging packages, l4js focuses on ease of use, reusability, and a streamlined "create once, use everywhere" pattern. With l4js, there's no need for complex instantiation or configuration—just quick, intuitive logging that gets out of your way.

Key features include:

• Small and Lightweight: Minimal footprint with no unnecessary dependencies.
• Easy to Use: Simple setup and straightforward API, perfect for developers of all experience levels.
• Reusable: Design once, and reuse your logger configuration across your entire project.
• No Complex Instantiation: Say goodbye to cumbersome configuration; l4js gets you logging instantly.
• l4js is the perfect tool for developers seeking a hassle-free logging solution that just works.

Quick Start

Getting Started is easy and quick !

install l4js

$ npm install l4js@latest

Simple Logging Examples

Import The Library into project or app.

/* Import l4js into your Application */
let {L4js} = require("L4js");

Create an options or configuration Object

let options = {
        dateFormat:"",     // A Date Format Default is "yyyy-MM-dd"
        filePath:"",       // The File path where the log file file should be placed if logging to file is enabled 
        logLevel:"*",      // The Log Level Default is * (Supports All Levels). you can choose info|warn|error|debug
        logToFile: false,  // boolean flag to enable or disable logging to a file default is false
        fileName: null,    // Your desired log filename if logging to file is enabled Default is "l4js.yyyy-MM-dd.log"
        batchSize: 0,      // Log Queue Batch size (default is 0)  
        flushInterval: 0   // The Log Queue flush interval to clear and write logs from a log queue 
} 

Initialize the Logger

let logger = L4js.initialize(options) 

Log a Simple Info Message

logger.info("This is a Info Message");

Log a Warning Message

logger.warn("This is a Warning Message");

Log A Error Message

logger.error(new Error("I messed up Something"));

Log a Debug Message

logger.debug("This is a Debug Message, In some app.. What is going on? ");

Example Log Output:

# INFO Message 
2024-08-23 INFO (60103) "This is a Info Message"

# WARN Message
2024-08-23 WARN (60103) "This is a Warning Message"

# ERROR Message
2024-08-23 ERROR (60103)
["Error","I messed up Something","Error: I messed up Something\n    at Object.<anonymous> l4js/test/index.js:14:14)\n    at Module._compile (node:internal/modules/cjs/loader:1358:14)\n    at Module._extensions..js (node:internal/modules/cjs/loader:1416:10)\n    at Module.load (node:internal/modules/cjs/loader:1208:32)\n    at Module._load (node:internal/modules/cjs/loader:1024:12)\n    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:174:12)\n    at node:internal/main/run_main_module:28:49"]

# DEBUG Message
2024-08-23 DEBUG (60103) "This is a Debug Message, In some app.. What is going on? "

Options

There are couple of options you can provide when you instantiate a l4js instance

| name | description | | :------------ | :------------------------------------------------------------------------------------------- | | dateFormat | A Date Format Default is "yyyy-MM-dd" | | filePath | The File path where the log file file should be placed if logging to file is enabled | | logLevel | The Log Level Default is * (Supports All Levels). you can choose info|warn|error|debug | | logToFile | boolean flag to enable or disable logging to a file default is false | | fileName | Your desired log filename if logging to file is enabled Default is "l4js.yyyy-MM-dd.log" | | batchSize | Log Queue Batch size (default is 0) | | flushInterval | The Log Queue flush interval to clear and write logs from a log queue |

File Writes

Writing logs to file is a common use case with l4js it very easy to start logging your precious content to a file.

whenever you instantiate or create a new l4js object make sure you set the logToFile alway to true if you would like to log content to a given file.

l4js can either name the name file for you by using the default log file name l4js.yyyy-MM-dd.log or you van choose another name by providing your custom file name to with fileName parameter!

l4js provides 2 file Logging Strategies

1. Write the Log immediately to file with every info(), warn(), error(), debug() invocation
2. Store Logs in a Log Queue with a predefined size allocated once it exceed the the predefined size batchSize the queue is Flushed and written to log file.
3. Flush the Queue at intervals flushInterval sometime its nice to not worry about anything if you provide a flushInterval (A interval in milliseconds) l4js will periodically check the LogQueue and flush it writing all Queue content to the given file.

Donations Welcome

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