@nasriya/overwatch

Overwatch.

Visit us at www.nasriya.net.

Made with ❤️ in Palestine 🇵🇸

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Overview

Overwatch is a fast, reliable, and efficient file system watcher built with TypeScript. It supports flexible filtering using globs and regexes, making it ideal for scalable, cross-platform file monitoring with minimal resource usage.

[!IMPORTANT]

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Installation

npm i @nasriya/overwatch

Importing

Import in ES6 module

import overwatch from '@nasriya/overwatch';

Import in CommonJS (CJS)

const overwatch = require('@nasriya/overwatch').default;

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Usage

1. Defining watchers

📁 Watching Directories (Folders)

Use overwatch.watchFolder() (recommended) or overwatch.watch() to watch a directory. You can optionally provide filters to include or exclude specific paths:

// Strongly recommended: use `watchFolder` for directories
const projectWatcher = await overwatch.watchFolder(process.cwd(), {
   include: ['**/*.ts'], // Accepts globs, regex, or absolute paths
   exclude: [/node_modules/, '**/*.test.ts'],
});

Or without watching options:

const projectWatcher = await overwatch.watchFolder(process.cwd());

📄 Watching Files

You can also watch indivisual files:

const fileWatcher = await overwatch.watchFile('src/config.json');

2. Handling events

You can attach a general handler for all change events:

// Handles all the watcher's events
projectWatcher.onChange(({ type, event }) => {
    // Handle different event types
    switch (type) {
        case 'add':
            console.log(`Added ${event.type}: ${event.path}`);
            break;
        case 'remove':
            console.log(`Removed ${event.type}: ${event.path}`);
            break;
        case 'rename':
            console.log(`Renamed ${event.type}: ${event.oldPath} -> ${event.newPath}`);
            break;
        case 'update':
            console.log(`Updated ${event.type}: ${event.path}`);
            break;
        case 'rootRemoved':
            console.log(`Watcher root was deleted`);
            break;
    }

    // NOTE: `event.type` is the type of the changed item, either `File` or `Folder`
});

Or, register dedicated handlers for specific events:

projectWatcher.onAdd((path) => {
   console.log(`Added: ${path}`);
});

projectWatcher.onRemove((event) => {
   console.log(`${event.type} removed: ${event.path}`);
});

projectWatcher.onRename((event) => {
   console.log(`${event.type} renamed: ${event.oldPath} -> ${event.newPath}`);
});

projectWatcher.onUpdate((event) => {
   console.log(`${event.type} updated: ${event.path}`);
});

You can also pass the handlers when you create the watcher:

const projectWatcher = await overwatch.watchFolder(process.cwd(), {
   include: ['**/*.ts'], // Accepts globs, regex, or absolute paths
   exclude: [/node_modules/, '**/*.test.ts'],
   onRename: (event) => {
        console.log(`${event.type} renamed: ${event.oldPath} -> ${event.newPath}`);
   }
});

3. Handling Root Deletion

If the root directory being watched is deleted, a special event is triggered:

projectWatcher.onRootRemoved(() => {
   console.log('The watched directory was deleted.');
});

Notes

• ✅ include and exclude accept absolute paths, glob patterns (e.g., '**/*.ts'), and regular expressions (e.g., /\.test\.ts$/).
• ✅ Prefer watchFolder() and watchFile() over the general watch() method for clearer intent and improved readability.
• 📌 All watchers share a single internal engine — multiple watchers on the same path won't trigger redundant scans.
• ⚠️ Filters (include, exclude) do not impact scanning performance; they only determine which changes are emitted to the user.
• 📁 event.type refers to the type of the changed item — either 'File' or 'Folder'.
• 🧠 Each watcher allows only one handler per event type — setting a new handler (e.g., via onChange) will replace the previous one.
• 🚫 If the root directory being watched is deleted, the watcher is automatically removed, and a rootRemoved event is emitted.
• ℹ️ The root is always a directory — even when watching a file, the root refers to its parent folder.
• ⏸️ Use overwatch.control.pause() and overwatch.control.resume() to temporarily stop and restart the internal scanning engine without removing watchers.
• 🔄 While paused, no file system changes are detected or emitted; resuming triggers an immediate scan and continues monitoring.
• ✅ These control methods are safe to call multiple times and do not affect watcher registration or state.

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License

This software is licensed under the Nasriya Open License (NOL), version 1.0. Please read the license from here.