Grunt

The topic describes how to install and configure Grunt JavaScript task runner.

You can use Grunt to automate any tasks you need, but out of the box the application comes with pre-configured grunt tasks for compiling LESS files.

Prerequisites

Make sure that you set your application to the developer or default mode.

Install and configure Grunt

The application has built-in Grunt tasks configured, but there are still several steps you need to take to be able to use it:

Install node.js to any location on your machine.
Install Grunt CLI tool globally. To do this, run the following command in a command prompt:
```
npm install -g grunt-cli
```
From the <Magento_root> directory, copy and paste the contents of the following files:
- package.json.sample into package.json
- Gruntfile.js.sample into Gruntfile.js
- grunt-config.json.sample into grunt-config.json
Install (or refresh) the node.js project dependency, including Grunt, for your instance. To do this, run the following commands in a command prompt:
```
cd your_Magento_instance_directory
```
```
npm install
```
```
npm update
```

Configuration file

Copy the contents of themes.js into local-themes.js in the dev/tools/grunt/configs/ directory.

If installed as described above, Grunt will use the default configuration files located in the dev/tools/grunt/configs/ directory. You can define your theme in the local-themes.js file. The following shows an example of how you can define your theme.

<theme>: {
  area: '<area>',
  name: '<Vendor>/<theme>,
  locale: '<language>',
  files: [
    '<path_to_file1>', //path to root source file
    '<path_to_file2>'
  ],
dsl: 'less'
}

Where the following notation is used:

<Vendor>: vendor name.
<theme>: your theme code, conventionally should correspond to the theme directory name.
<area>: area code, can be either frontend or adminhtml.
<language>: specified in the code_subtag format, for example en_US. Only one locale can be specified here. To debug the theme with another locale, create one more theme declaration, having specified another value for language.
<path_to_file>: path to the root source file, relative to the app/design/frontend/<Vendor>/<theme>/web directory. You need to specify all root source files of the theme. If your theme [inherits] from a certain theme, and does not contain its own root source files, specify the root source files of the parent theme.

Once these are set correctly, run grunt to watch your changes.

Run grunt exec:<theme> from the root directory to republish the symlinks.
Run grunt watch:<theme> so that grunt will watch for file changes.

Custom Grunt configuration files

There are several ways to declare a custom configuration file.

Declare a custom configuration file (option 1)

To use a custom file for Grunt configuration:

Copy the default configuration file to the preferred location in the instance directory. Do not change the file name.
Open the grunt-config.json file in the installation and set configurations object as follows.
- key: file alias
- value: path to your custom file
Example: If your custom configuration file local-themes.js is located in the <magento_root>/dev/tools/grunt/configs directory, the following is already set in your grunt-config.json:
```
{
    "themes": "dev/tools/grunt/configs/local-themes.js"
}
```

This path is also added to your .gitignore by default.

Declare a custom configuration file (option 2)

You can also use the other way to declare a custom config file:

In your Grunt related scripts, in the file router, set the alias and path to the custom configuration file. For example, to set the custom themes.loc.js configuration file, this would look like the following:
```
filesRouter.set('themes', 'dev/tools/grunt/configs/themes.loc.js');
```
It must be added earlier, than the get() method with this alias is called.
In the dev/tools/grunt/configs/ directory, create a copy of the default configuration file. Change its name by adding the ".loc" suffix. For example, your copy of themes.js will be themes.loc.js.

How to use a custom configuration file

To tell Grunt to use a custom configuration file, instead of the default one, add the following in your script:

Require file-router:

var fileRouter = require('/files-router');

Call the get(%file_alias%) method to get the configuration file.
```
var themes = fileRouter.get('themes');
```