diff --git a/core/modules/block_place/block_place.module b/core/modules/block_place/block_place.module
index dc0b7efe29..e7a9c23c8b 100644
--- a/core/modules/block_place/block_place.module
+++ b/core/modules/block_place/block_place.module
@@ -94,7 +94,8 @@ function block_place_toolbar() {
  * Add block place library if dialog should be open to sort blocks.
  */
 function block_place_page_attachments(array &$attachments) {
-  if ($region_sort = \Drupal::request()->query->get('block-place-region-sort')) {
+  $query = \Drupal::request()->query;
+  if ($region_sort = $query->get('block-place-region-sort')) {
     $attachments['#attached']['library'][] = 'block_place/drupal.block_place.js';
     $destination = \Drupal::destination()->get();
     $destination = explode('?', $destination)[0];
@@ -106,6 +107,8 @@ function block_place_page_attachments(array &$attachments) {
       'dialog_type' => \Drupal::moduleHandler()->moduleExists('outside_in') ? 'dialog_off_canvas' : 'modal',
     ];
   }
+  // Save a setting to flag pages where block_place mode is active.
+  $attachments['#attached']['drupalSettings']['block_place']['isInBlockPlaceMode'] = ($region_sort || $query->get('block-place'));
 }
 
 /**
diff --git a/core/modules/block_place/js/block_place.es6.js b/core/modules/block_place/js/block_place.es6.js
index 3d33648a0e..92ef736901 100644
--- a/core/modules/block_place/js/block_place.es6.js
+++ b/core/modules/block_place/js/block_place.es6.js
@@ -4,11 +4,6 @@
  */
 
 (function ($, window, Drupal, drupalSettings) {
-
-  'use strict';
-
-  Drupal.blockPlace.isBlockPlaceMode = true;
-
   Drupal.behaviors.blockPlace = {
     attach(context, settings) {
       // If drupalSettings.block_place is set open open dialog.
diff --git a/core/modules/block_place/js/block_place.js b/core/modules/block_place/js/block_place.js
index 6638a3a5c7..3c2d40479b 100644
--- a/core/modules/block_place/js/block_place.js
+++ b/core/modules/block_place/js/block_place.js
@@ -6,28 +6,16 @@
 **/
 
 (function ($, window, Drupal, drupalSettings) {
-
-  'use strict';
-
-  Drupal.blockPlace = {
-    isBlockPlaceMode: function isBlockPlaceMode() {
-      var queryString = decodeURI(window.location.search);
-      return (/block-place=1/i.test(queryString) || /block-place-region-sort=/i.test(queryString)
-      );
-    }
-  };
-
   Drupal.behaviors.blockPlace = {
     attach: function attach(context, settings) {
       if (drupalSettings.hasOwnProperty('block_place') && drupalSettings.block_place.hasOwnProperty('dialog_url')) {
         $(window).once('block_sort').each(function () {
-          var blockSort = Drupal.ajax({
+          Drupal.ajax({
             dialog: {},
             dialogType: drupalSettings.block_place.dialog_type,
             url: drupalSettings.block_place.dialog_url,
             progress: { type: 'throbber' }
-          });
-          blockSort.execute();
+          }).execute();
         });
       }
     }
diff --git a/core/modules/outside_in/js/outside_in.es6.js b/core/modules/outside_in/js/outside_in.es6.js
index 883ee66a33..077ad3bdb0 100644
--- a/core/modules/outside_in/js/outside_in.es6.js
+++ b/core/modules/outside_in/js/outside_in.es6.js
@@ -3,7 +3,7 @@
  * Drupal's Settings Tray library.
  */
 
-(function ($, Drupal) {
+(function ($, Drupal, drupalSettings) {
   const blockConfigureSelector = '[data-outside-in-edit]';
   const toggleEditSelector = '[data-drupal-outsidein="toggle"]';
   const itemsToToggleSelector = '[data-off-canvas-main-canvas], #toolbar-bar, [data-drupal-outsidein="editable"] a, [data-drupal-outsidein="editable"] button';
@@ -194,7 +194,7 @@
       const editMode = localStorage.getItem('Drupal.contextualToolbar.isViewing') === 'false';
       if (editMode) {
         // Do turn on edit mode when on block
-        if (!Drupal.hasOwnProperty('blockPlace') || !Drupal.blockPlace.isBlockPlaceMode()) {
+        if (!drupalSettings.hasOwnProperty('block_place') || !drupalSettings.block_place.isInBlockPlaceMode) {
           setEditModeState(true);
         }
       }
@@ -260,4 +260,4 @@
       }
     },
   });
-}(jQuery, Drupal));
+}(jQuery, Drupal, drupalSettings));
diff --git a/core/modules/outside_in/js/outside_in.js b/core/modules/outside_in/js/outside_in.js
index 1019eea683..326aff5754 100644
--- a/core/modules/outside_in/js/outside_in.js
+++ b/core/modules/outside_in/js/outside_in.js
@@ -5,7 +5,7 @@
 * @preserve
 **/
 
-(function ($, Drupal) {
+(function ($, Drupal, drupalSettings) {
   var blockConfigureSelector = '[data-outside-in-edit]';
   var toggleEditSelector = '[data-drupal-outsidein="toggle"]';
   var itemsToToggleSelector = '[data-off-canvas-main-canvas], #toolbar-bar, [data-drupal-outsidein="editable"] a, [data-drupal-outsidein="editable"] button';
@@ -116,7 +116,7 @@
     attach: function attach() {
       var editMode = localStorage.getItem('Drupal.contextualToolbar.isViewing') === 'false';
       if (editMode) {
-        if (!Drupal.hasOwnProperty('blockPlace') || !Drupal.blockPlace.isBlockPlaceMode()) {
+        if (!drupalSettings.hasOwnProperty('block_place') || !drupalSettings.block_place.isInBlockPlaceMode) {
           setEditModeState(true);
         }
       }
@@ -168,4 +168,4 @@
       }
     }
   });
-})(jQuery, Drupal);
\ No newline at end of file
+})(jQuery, Drupal, drupalSettings);
\ No newline at end of file