woocommerce/plugins/woocommerce-admin/docs/feature-flags.md

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# Feature Flags
Features inside the `wc-admin` repository can be in various states of completeness. In addition to the development copy of `wc-admin`, feature plugin versions are bundled, and code is merged to WooCommerce core. To provide a way for improved control over how these features are released in these different environments, `wc-admin` has a system for feature flags.
We currently support the following environments:
| Environment | Description |
|-------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| development | Development - All features should be enabled in development. These flags are also used in both JS and PHP tests. Ran using `npm start`. |
| plugin | Plugin - A packaged release of the featured plugin, for GitHub WordPress.org. Ran using `npm run-script build:release`. | |
| core | Core - assets/files ready and stable enough for core merge. Ran using `npm pack`. (@todo update this with publish command).
## Adding a new flag
Flags can be added to the files located in the `config/` directory. Make sure to add a flag for each environment and explicitly set the flag to false.
Please add new feature flags alphabetically so they are easy to find.
## Basic Use - Client
The `window.wcAdminFeatures` constant is a global variable containing the feature flags.
Instances of `window.wcAdminFeatures` are replaced during the webpack build process by using webpack's [define plugin](https://webpack.js.org/plugins/define-plugin/). Using `webpack` for this allows us to eliminate dead code when making minified/production builds (`plugin`, or `core` environments).
To check if a feature is enabled, you can simplify check the boolean value of a feature:
```
{ window.wcAdminFeatures[ 'activity-panels' ] && <ActivityPanel /> }
```
We also expose CSS classes on the `body` tag, so that you can target specific feature states when they are enabled:
```
<body class="wp-admin woocommerce-page woocommerce-feature-enabled-activity-panels ....">
```
## Basic Use - Server
Feature flags are also available via PHP. To ensure these are consistent with the built client assets, `includes/feature-flags.php` is generated by the plugin build process or `npm start`. Do not edit `includes/feature-flags.php` directly.
To check if a feature is enabled, you can use the `WC_Admin_Loader::is_feature_enabled()`:
```
if ( WC_Admin_Loader::is_feature_enabled( 'activity-panels' ) ) {
add_action( 'admin_header', 'wc_admin_activity_panel' );
}
```
If you name a directory after the flag in `includes/` with a `class-wc-admin-FEATURE.php` file, this code will also automatically be loaded.