70 lines
3.3 KiB
Markdown
70 lines
3.3 KiB
Markdown
# Cheap Watch: If it works, why use something else?
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[](https://www.npmjs.com/package/cheap-watch)
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**Cheap Watch** is a small, simple, dependency-free, cross-platform file system watcher for Node.js 8+.
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## Constructor
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### `new CheapWatch({ dir, filter, watch = true, debounce = 10 })`
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- `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`.
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- `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.
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- `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.
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- `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.
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## Methods
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### `cheapWatch.init()`
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Initialize the watcher, traverse the directory to find the initial files and directories, and set up watchers to look for changes.
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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.
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### `cheapWatch.close()`
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Close all `FSWatcher` instances, and stop watching for file changes.
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## Properties
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### `cheapWatch.files`
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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.
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You can use `stats.isFile()` and `stats.isDirectory()` to determine whether something is a file or a directory.
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## Events
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A `CheapWatch` is an `EventEmitter`, and emits two events to report a new, updated, or deleted file or directory.
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### `+` `{ path, stats }`
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A `+` event is emitted with an object containing a `path` string and a `stats` object whenever a watched file or directory is created or updated.
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### `-` `{ path, stats }`
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A `-` event is emitted with an object containing a `path` string and a `stats` object whenever a watched file or directory is deleted. `stats` will be the most recent `Stats` collected for the file or directory before it was deleted.
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## Usage
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```javascript
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import CheapWatch from 'cheap-watch';
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const watcher = new CheapWatch({ dir, /* ... */ });
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await watcher.init();
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for (const [path, stats] of watcher.files) {
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/* ... */
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}
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watcher.on('+', ({ path, stats }) => { /* ... */ });
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watcher.on('-', ({ path, stats }) => { /* ... */ });
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```
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## License
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Copyright (c) 2018 Conduitry
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- [MIT](LICENSE)
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