# Cheap Watch: If it works, why use something else? [![npm version](https://img.shields.io/npm/v/cheap-watch.svg?style=flat-square)](https://www.npmjs.com/package/cheap-watch) [![Build Status](https://travis-ci.org/Conduitry/cheap-watch.svg?branch=master)](https://travis-ci.org/Conduitry/cheap-watch) **Cheap Watch** is a small, simple, dependency-free, cross-platform file system watcher for Node.js 8+. ## Constructor ### `new CheapWatch({ dir, filter, watch = true, debounce = 10 })` - `dir` - The directory whose contents to watch. It's recommended, though not required, for this to be an absolute path, say one returned by `path.resolve`. - `filter({ path, stats })` - _(optional)_ A function to decide whether a given file or directory should be watched. It's passed an object containing the file or directory's relative `path` and its `stats`. It should return `true` or `false` (or a `Promise` resolving to one of those). Returning `false` for a directory means that none of its contents will be watched. - `watch` - _(optional)_ Whether to actually watch the directory for changes. Defaults to `true`. If `false`, you can retrieve all of the files and directories within a given directory along with their initial `Stats` but changes will not be monitored. - `debounce` - _(optional)_ Length of timeout in milliseconds to use to debounce incoming events from `fs.watch`. Defaults to 10. Multiple events are often emitted for a single change, and events can also be emitted before `fs.stat` reports the changes. So we will wait until `debounce` milliseconds have passed since the last `fs.watch` event for a file or directory before handling it. The default of 10ms Works On My Machine. ## Methods ### `init()` Initialize the watcher, traverse the directory to find the initial files and directories, and set up watchers to look for changes. This returns a `Promise` that resolves once the initial contents of the directory have been traversed and all of the watchers have been set up. ### `close()` Close all `FSWatcher` instances, and stop watching for file changes. ## Properties ### `paths` A `Map` of the watched files and directories. Each key is a relative path from the `CheapWatch`'s `dir`, and each value is a `Stats` object for the file or directory. Paths are always separated by forward slashes, regardless of platform. This `Map` is kept up to date as files are changed on disk. You can use `stats.isFile()` and `stats.isDirectory()` to determine whether something is a file or a directory. ## Events A `CheapWatch` is an `EventEmitter`, and emits two events to report a new, updated, or deleted file or directory. ### `+` `{ path, stats, isNew }` A `+` event is emitted whenever a watched file or directory is created or updated. It's emitted with an object containing a `path` string, a `stats` object, and an `isNew` boolean which will be `true` for newly created files and directories and `false` for updated ones. ### `-` `{ path, stats }` A `-` event is emitted whenever a watched file or directory is deleted. It's emitted with an object containing a `path` string and a `stats` object. `stats` will be the most recent `Stats` collected for the file or directory before it was deleted. ## Usage ```javascript import CheapWatch from 'cheap-watch'; const watch = new CheapWatch({ dir, /* ... */ }); await watch.init(); for (const [path, stats] of watch.paths) { /* ... */ } watch.on('+', ({ path, stats, isNew }) => { /* ... */ }); watch.on('-', ({ path, stats }) => { /* ... */ }); ``` ## License [MIT](LICENSE)