diff -u b/core/modules/ckeditor/src/Plugin/Editor/CKEditor.php b/core/modules/ckeditor/src/Plugin/Editor/CKEditor.php
--- b/core/modules/ckeditor/src/Plugin/Editor/CKEditor.php
+++ b/core/modules/ckeditor/src/Plugin/Editor/CKEditor.php
@@ -248,7 +248,7 @@
   /**
    * {@inheritdoc}
    */
-  public function getJSConfiguration(EditorEntity $editor) {
+  public function getJsConfiguration(EditorEntity $editor) {
     $settings = array();
 
     // Get the settings for all enabled plugins, even the internal ones.
@@ -369,7 +369,7 @@
   /**
    * Builds the "toolbar" configuration part of the CKEditor JS settings.
    *
-   * @see getJSConfiguration()
+   * @see getJsConfiguration()
    *
    * @param \Drupal\editor\Entity\Editor $editor
    *   A configured text editor object.
@@ -392,7 +392,7 @@
   /**
    * Builds the "contentsCss" configuration part of the CKEditor JS settings.
    *
-   * @see getJSConfiguration()
+   * @see getJsConfiguration()
    *
    * @param \Drupal\editor\Entity\Editor $editor
    *   A configured text editor object.
diff -u b/core/modules/ckeditor/src/Tests/CKEditorTest.php b/core/modules/ckeditor/src/Tests/CKEditorTest.php
--- b/core/modules/ckeditor/src/Tests/CKEditorTest.php
+++ b/core/modules/ckeditor/src/Tests/CKEditorTest.php
@@ -71,7 +71,7 @@
   }
 
   /**
-   * Tests CKEditor::getJSConfiguration().
+   * Tests CKEditor::getJsConfiguration().
    */
   function testGetJSSettings() {
     $editor = entity_load('editor', 'filtered_html');
@@ -95,7 +95,7 @@
       ),
     );
     ksort($expected_config);
-    $this->assertIdentical($expected_config, $this->ckeditor->getJSConfiguration($editor), 'Generated JS settings are correct for default configuration.');
+    $this->assertIdentical($expected_config, $this->ckeditor->getJsConfiguration($editor), 'Generated JS settings are correct for default configuration.');
 
     // Customize the configuration: add button, have two contextually enabled
     // buttons, and configure a CKEditor plugin setting.
@@ -119,7 +119,7 @@
     $expected_config['drupalExternalPlugins']['llama_contextual_and_button'] = file_create_url('core/modules/ckeditor/tests/modules/js/llama_contextual_and_button.js');
     $expected_config['contentsCss'][] = file_create_url('core/modules/ckeditor/tests/modules/ckeditor_test.css');
     ksort($expected_config);
-    $this->assertIdentical($expected_config, $this->ckeditor->getJSConfiguration($editor), 'Generated JS settings are correct for customized configuration.');
+    $this->assertIdentical($expected_config, $this->ckeditor->getJsConfiguration($editor), 'Generated JS settings are correct for customized configuration.');
 
     // Change the allowed HTML tags; the "allowedContent" and "format_tags"
     // settings for CKEditor should automatically be updated as well.
@@ -130,7 +130,7 @@
     $expected_config['allowedContent']['pre'] = array('attributes' => TRUE, 'styles' => FALSE, 'classes' => TRUE);
     $expected_config['allowedContent']['h3'] = array('attributes' => TRUE, 'styles' => FALSE, 'classes' => TRUE);
     $expected_config['format_tags'] = 'p;h3;h4;h5;h6;pre';
-    $this->assertIdentical($expected_config, $this->ckeditor->getJSConfiguration($editor), 'Generated JS settings are correct for customized configuration.');
+    $this->assertIdentical($expected_config, $this->ckeditor->getJsConfiguration($editor), 'Generated JS settings are correct for customized configuration.');
 
     // Disable the filter_html filter: allow *all *tags.
     $format->setFilterConfig('filter_html', array('status' => 0));
@@ -139,7 +139,7 @@
     $expected_config['allowedContent'] = TRUE;
     $expected_config['disallowedContent'] = FALSE;
     $expected_config['format_tags'] = 'p;h1;h2;h3;h4;h5;h6;pre';
-    $this->assertIdentical($expected_config, $this->ckeditor->getJSConfiguration($editor), 'Generated JS settings are correct for customized configuration.');
+    $this->assertIdentical($expected_config, $this->ckeditor->getJsConfiguration($editor), 'Generated JS settings are correct for customized configuration.');
 
     // Enable the filter_test_restrict_tags_and_attributes filter.
     $format->setFilterConfig('filter_test_restrict_tags_and_attributes', array(
@@ -208,12 +208,12 @@
     );
     $expected_config['format_tags'] = 'p';
     ksort($expected_config);
-    $this->assertIdentical($expected_config, $this->ckeditor->getJSConfiguration($editor), 'Generated JS settings are correct for customized configuration.');
+    $this->assertIdentical($expected_config, $this->ckeditor->getJsConfiguration($editor), 'Generated JS settings are correct for customized configuration.');
 
     // Assert that we're robust enough to withstand people messing with State
     // manually.
     \Drupal::state()->delete('ckeditor_internal_format_tags:' . $format->id());
-    $this->assertIdentical($expected_config, $this->ckeditor->getJSConfiguration($editor), 'Even when somebody manually deleted the key-value pair in State with the pre-calculated format_tags setting, it returns "p" — because the <p> tag is always allowed.');
+    $this->assertIdentical($expected_config, $this->ckeditor->getJsConfiguration($editor), 'Even when somebody manually deleted the key-value pair in State with the pre-calculated format_tags setting, it returns "p" — because the <p> tag is always allowed.');
   }
 
   /**
@@ -386,7 +386,7 @@
     $this->installSchema('locale', 'locales_location');
     $this->installSchema('locale', 'locales_target');
     $editor = Editor::load('filtered_html');
-    $this->ckeditor->getJSConfiguration($editor);
+    $this->ckeditor->getJsConfiguration($editor);
     $localeStorage = $this->container->get('locale.storage');
     $string = $localeStorage->findString(array('source' => 'Edit Link', 'context' => ''));
     $this->assertTrue(!empty($string), 'String from JavaScript file saved.');
@@ -414,7 +414,7 @@
 
     // Test that we now get the expected language.
     $editor = Editor::load('filtered_html');
-    $settings = $this->ckeditor->getJSConfiguration($editor);
+    $settings = $this->ckeditor->getJsConfiguration($editor);
     $this->assertEqual($settings['language'], $langcode);
   }