Module-Monitor

Module-Monitor facilitates automatic reloading of modules in Node.js applications, ensuring real-time updates during development.

About The Project

Modul-Monitor is a lightweight utility for Node.js applications that enables automatic reloading of modules when they are modified. It provides a seamless development experience by monitoring specified directories for file changes and refreshing the modules accordingly, ensuring that the latest code changes are always reflected during development.

Features

• WatchFile: Monitor a single module file for changes, reload dynamically, and handle cleanup.
• WatchFolder: Monitor an entire directory for module additions, changes, and deletions.
• Cache Management: Automatic cache-busting and cleanup via query parameters and cleanupModule support.
• TypeScript Support: Written entirely in TypeScript with typings included.

Installation

npm install module-monitor

Usage

CommonJS

const { WatchFile, WatchFolder } = require("module-monitor");

ES6

import { WatchFile, WatchFolder } from "module-monitor";

WatchFile Example

config.js

function getConfig(){
    return { name: 'XanderID' };
}

export default { getConfig }

index.js

import { WatchFile } from "module-monitor";

const watcher = new WatchFile("./config.js");

watcher.setOnChange(path => {
  console.log(`File changed: ${path}`);
});

watcher.setOnReload((mod, file, err) => {
  if (err) console.error("Reload failed:", err);
  else console.log("Config reloaded:", mod.default.getConfig());
});

watcher.setOnDelete(path => {
  console.log(`File deleted: ${path}`);
});

WatchFolder Example

import { WatchFolder } from "module-monitor";

const commands = new WatchFolder("./commands");

commands.setOnAdd(path => console.log(`Module added: ${path}`));
commands.setOnChange(path => console.log(`Module updated: ${path}`));
commands.setOnDelete(path => console.log(`Module removed: ${path}`));
commands.setOnReload((mod, file, err) => {
  if (err) console.error("Reload error:", err);
  else console.log(`Module loaded:`, mod);
});

Warning

If your modules perform ongoing tasks (e.g., setInterval), implement and export a cleanupModule function to prevent duplicate operations on reload.

Usage Example (e.g., message.js):

let messages = [];
let counter = 1;
const interval = setInterval(() => {
  messages.push(`This is message #${counter}`);
  counter++;
}, 1000);

export async function cleanupModule() {
  clearInterval(interval);
}

This ensures old intervals are cleared before reloading, avoiding duplicate timers or resource leaks.

API

• WatchFile<T>

  • constructor(filePath: string)
  • setOnChange(cb: (path: string) => void)
  • setOnReload(cb: (mod: T | null, filePath: string, err?: Error) => void)
  • setOnDelete(cb: (path: string) => void)
  • cleanup(): Promise<void>

• WatchFolder<T>

  • constructor(folderPath: string)
  • setOnAdd(cb: (path: string) => void)
  • setOnChange(cb: (path: string) => void)
  • setOnDelete(cb: (path: string) => void)
  • setOnReload(cb: (mod: T | null, filePath: string, err?: Error) => void)
  • cleanup(): Promise<void>

Contributing

Contributions are welcome! Please open issues and pull requests on GitHub.

License

Distributed under the MIT License.