Initial Drupal 11 with DDEV setup

web/core/modules/system/js/system.js

@@ -0,0 +1,82 @@
+/**
+ * @file
+ * System behaviors.
+ */
+
+(function ($, Drupal, drupalSettings) {
+  // Cache IDs in an array for ease of use.
+  const ids = [];
+
+  /**
+   * Attaches field copy behavior from input fields to other input fields.
+   *
+   * When a field is filled out, apply its value to other fields that will
+   * likely use the same value. In the installer this is used to populate the
+   * administrator email address with the same value as the site email address.
+   *
+   * @type {Drupal~behavior}
+   *
+   * @prop {Drupal~behaviorAttach} attach
+   *   Attaches the field copy behavior to an input field.
+   */
+  Drupal.behaviors.copyFieldValue = {
+    attach(context) {
+      // List of fields IDs on which to bind the event listener.
+      // Create an array of IDs to use with jQuery.
+      Object.keys(drupalSettings.copyFieldValue || {}).forEach((element) => {
+        ids.push(element);
+      });
+
+      if (ids.length) {
+        // Listen to value:copy events on all dependent fields.
+        // We have to use body and not document because of the way jQuery events
+        // bubble up the DOM tree.
+        $(once('copy-field-values', 'body')).on(
+          'value:copy',
+          this.valueTargetCopyHandler,
+        );
+        // Listen on all source elements.
+        $(once('copy-field-values', `#${ids.join(', #')}`)).on(
+          'blur',
+          this.valueSourceBlurHandler,
+        );
+      }
+    },
+    detach(context, settings, trigger) {
+      if (trigger === 'unload' && ids.length) {
+        $(once.remove('copy-field-values', 'body')).off('value:copy');
+        $(once.remove('copy-field-values', `#${ids.join(', #')}`)).off('blur');
+      }
+    },
+
+    /**
+     * Event handler that fill the target element with the specified value.
+     *
+     * @param {jQuery.Event} e
+     *   Event object.
+     * @param {string} value
+     *   Custom value from jQuery trigger.
+     */
+    valueTargetCopyHandler(e, value) {
+      const { target } = e;
+      if (target.value === '') {
+        target.value = value;
+      }
+    },
+
+    /**
+     * Handler for a Blur event on a source field.
+     *
+     * This event handler will trigger a 'value:copy' event on all dependent
+     * fields.
+     *
+     * @param {jQuery.Event} e
+     *   The event triggered.
+     */
+    valueSourceBlurHandler(e) {
+      const { value } = e.target;
+      const targetIds = drupalSettings.copyFieldValue[e.target.id];
+      $(`#${targetIds.join(', #')}`).trigger('value:copy', value);
+    },
+  };
+})(jQuery, Drupal, drupalSettings);