diff --git a/core/modules/file/file.js b/core/modules/file/file.js
index abf99fe..c1283ee 100644
--- a/core/modules/file/file.js
+++ b/core/modules/file/file.js
@@ -107,15 +107,16 @@
       if (extensionPattern.length > 1 && event.target.value.length > 0) {
         var acceptableMatch = new RegExp('\\.(' + extensionPattern + ')$', 'i');
         var testSubjects;
-        if(event.target.files) {
+        if (event.target.files) {
           testSubjects = event.target.files;
-        } else {
+        }
+        else {
           testSubjects = [{name: event.target.value}];
         }
         var invalidFiles = [];
-        for(var i = 0; i < testSubjects.length; i++) {
+        for (var i = 0; i < testSubjects.length; i++) {
           var testSubject = testSubjects[i];
-          if(!acceptableMatch.test(testSubject.name)) {
+          if (!acceptableMatch.test(testSubject.name)) {
             // According to the specifications of HTML5, a file upload control
             // should not reveal the real local path to the file that a user
             // has selected. Some web browsers implement this restriction by
@@ -130,9 +131,9 @@
           var error = Drupal.formatPlural(invalidFiles.length, 'The selected file %filename cannot be uploaded.', '@count of the selected files cannot be uploaded.', {
             '%filename': invalidFiles[0]
           });
-          if(invalidFiles.length > 1) {
+          if (invalidFiles.length > 1) {
             error += '<ul>';
-            for(var j = 0; j < invalidFiles.length; j++) {
+            for (var j = 0; j < invalidFiles.length; j++) {
               error += '<li>' + Drupal.formatString('%filename', {'%filename': invalidFiles[j]}) + '</li>';
             }
             error += '</ul>';
diff --git a/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php b/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
index abd0eec..5abd41c 100644
--- a/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
+++ b/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
@@ -280,15 +280,19 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
   }
 
   /**
-   * Form API callback. Attaches data- attributes to the file input field
-   * for JavaScript's benefit.
+   * Form API callback. Attaches data- attributes to the file input field for
+   * JavaScript's benefit.
    *
-   * @param array $element The FileWidget's render array
+   * @param array $element
+   *   The FileWidget's render array.
    * @param FormStateInterface $form_state
-   * @return array The updated render array
+   *   The form state.
+   *
+   * @return array
+   *   The updated render array.
    */
-  public function addValidateDataForJs($element, FormStateInterface &$form_state) {
-    // file extensions go on the ManagedFile's 'upload' child as data- attribute
+  public function addValidateDataForJs(array $element, FormStateInterface &$form_state) {
+    // File extensions go on the ManagedFile's 'upload' child as data attribute.
     if (is_array($element['upload']) && !empty($element['#upload_validators']['file_validate_extensions'])) {
       $element['upload']['#attributes']['data-drupal-validate-extensions'] = $element['#upload_validators']['file_validate_extensions'][0];
     }
@@ -398,7 +402,8 @@ public static function process($element, FormStateInterface $form_state, $form)
       );
       if (isset($item['display'])) {
         $element['display']['#value'] = $item['display'] ? '1' : '';
-      } else {
+      }
+      else {
         $element['display']['#value'] = $element['#display_default'];
       }
     }
diff --git a/core/modules/file/src/Tests/FileFieldWidgetTest.php b/core/modules/file/src/Tests/FileFieldWidgetTest.php
index e3d2626..6a245c8 100644
--- a/core/modules/file/src/Tests/FileFieldWidgetTest.php
+++ b/core/modules/file/src/Tests/FileFieldWidgetTest.php
@@ -347,7 +347,7 @@ function testWidgetValidation() {
       $test_file_image = $this->getTestFile('image');
       $name = 'files[' . $field_name . '_0]';
 
-      // check field is marked with expected attr for client-side validation
+      // Check field is marked with expected attr for client-side validation.
       $this->assertFieldByXPath('//input[@type="file" and @data-drupal-validate-extensions="txt"]', null, 'data-drupal-validate-extensions is present');
 
       // Upload file with incorrect extension, check for validation error.