# grunt-contrib-watch [![Build Status](https://secure.travis-ci.org/gruntjs/grunt-contrib-watch.png?branch=master)](http://travis-ci.org/gruntjs/grunt-contrib-watch)

> Run predefined tasks whenever watched file patterns are added, changed or deleted.

_Note that this plugin has not yet been released, and only works with the latest bleeding-edge, in-development version of grunt. See the [When will I be able to use in-development feature 'X'?](https://github.com/gruntjs/grunt/blob/devel/docs/faq.md#when-will-i-be-able-to-use-in-development-feature-x) FAQ entry for more information._

## Getting Started
_If you haven't used [grunt][] before, be sure to check out the [Getting Started][] guide._

From the same directory as your project's [Gruntfile][Getting Started] and [package.json][], install this plugin with the following command:

```bash
npm install grunt-contrib-watch --save-dev
```

Once that's done, add this line to your project's Gruntfile:

```js
grunt.loadNpmTasks('grunt-contrib-watch');
```

If the plugin has been installed correctly, running `grunt --help` at the command line should list the newly-installed plugin's task or tasks. In addition, the plugin should be listed in package.json as a `devDependency`, which ensures that it will be installed whenever the `npm install` command is run.

[grunt]: http://gruntjs.com/
[Getting Started]: https://github.com/gruntjs/grunt/blob/devel/docs/getting_started.md
[package.json]: https://npmjs.org/doc/json.html


## The watch task

### Overview

Inside your `Gruntfile.js` file, add a section named `watch`. This section specifies the files to watch, tasks to run when an event occurs and the options used.
### Settings

There are a number of options available. Please review the [minimatch options here](https://github.com/isaacs/minimatch#options). As well as some additional options as follows:

#### tasks
Type: `String|Array`

This defines which tasks to run when a watched file event occurs.

#### options.interrupt
Type: `boolean`
Default: false

As files are modified this watch task will spawn tasks in child processes. The default behavior will only spawn a new child process per target when the previous process has finished. Set the `interrupt` option to true to terminate the previous process and spawn a new one upon later changes.

Example:
```js
watch: {
  scripts: {
    files: '**/*.js',
    tasks: ['jshint'],
    options: {
      interrupt: true
    }
  }
}
```

#### options.debounceDelay
Type: `Integer`
Default: 500

How long to wait before emitting events in succession for the same filepath and status. For example if your `Gruntfile.js` file was `changed`, a `changed` event will only fire again after the given milliseconds.

Example:
```js
watch: {
  scripts: {
    files: '**/*.js',
    tasks: ['jshint'],
    options: {
      debounceDelay: 250
    }
  }
}
```

#### options.interval
Type: `Integer`
Default: 100

The `interval` is passed to `fs.watchFile`. Since `interval` is only used by `fs.watchFile` and this watcher also uses `fs.watch`; it is recommended to ignore this option. *Default is 100ms*.
### Examples

```js
// Simple config to run jshint any time a file is added, changed or deleted
grunt.initConfig({
  watch: {
    files: '**/*',
    tasks: ['jshint']
  }
});
```

```js
// Advanced config. Run specific tasks when specific files are added, changed or deleted.
grunt.initConfig({
  watch: {
    gruntfile: {
      files: 'Gruntfile.js',
      tasks: ['jshint:gruntfile'],
      options: {
        nocase: true
      }
    },
    src: {
      files: ['lib/*.js', 'css/**/*.scss', '!lib/dontwatch.js'],
      tasks: ['default']
    },
    test: {
      files: '<%= jshint.test.src %>',
      tasks: ['jshint:test', 'qunit']
    }
  }
});
```


## Release History

 * 2012-10-07 - v0.1.0 - Release watch task Remove spawn from helper Run on Grunt v0.4
 * 2012-10-15 - v0.1.1 - Fallback to global grunt bin if local doesnt exist. Fatal if bin cannot be found Update to gaze 0.1.6
 * 2012-10-16 - v0.1.2 - Only spawn a process per task one at a time Add interrupt option to cancel previous spawned process Grunt v0.3 compatibility changes

--
Task submitted by <a href="http://dontkry.com">Kyle Robinson Young</a>.

*Generated on Thu Oct 18 2012 17:23:15.*