Data attributes and feature flags

source/_notes/15.md

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+---
+title: "Data attributes and feature flags"
+date: 2024-08-26 21:34:15
+tags: [Web Development, Software Development, Feature Flags, Drupal, CSS, PHP]
+---
+
+I recently used the [Feature Toggle module](https://www.drupal.org/project/feature_toggle) to set a data attribute which enabled some new styling for buttons.
+
+## The PHP code
+
+In the theme's .theme file:
+
+```php
+/**
+ * Implements hook_preprocess_html().
+ */
+function mytheme_preprocess_html(array &$variables): void {
+  $variables['attributes']['data-use-new-button-styles'] = \Drupal::service('feature_toggle.feature_status')->getStatus('use_the_new_button_styling');
+}
+```
+
+If the feature toggle is enabled, this adds a `data-use-new-button-styles=""` attribute to the `body` element.
+
+## The CSS code
+
+```css
+[data-use-new-button-styles] .btn-primary {
+  background-color: red;
+}
+```
+
+I like using feature flags and was happy to find a way to use them for adding this new CSS.