Fix dob date validation on custom locale

Author: joachimVT

app/code/Magento/Customer/Block/Widget/Dob.php

@@ -209,24 +209,16 @@ public function getHtmlId()
     public function getHtmlExtraParams()
     {
         $validators = [];
-        $validators['required'] = true;
-        $validators['validate-date'] = [
-            'dateFormat' => $this->getDateFormat()
-        ];
-
-        return 'data-validate="' . $this->_escaper->escapeHtml(json_encode($validators)) . '"';
-
-        $extraParams = [
-            "'validate-date':true",
-        ];
 
         if ($this->isRequired()) {
-            $extraParams[] = 'required:true';
+            $validators['required'] = true;
         }
 
-        $extraParams = implode(', ', $extraParams);
+        $validators['validate-date'] = [
+            'dateFormat' => $this->getDateFormat()
+        ];
 
-        return 'data-validate="{' . $extraParams . '}"';
+        return 'data-validate="' . $this->_escaper->escapeHtml(json_encode($validators)) . '"';
     }
 
     /**

lib/web/mage/validation.js

@@ -973,6 +973,7 @@
                 return $.mage.isEmptyNoTrim(value) || test.isValid();
             },
             $.mage.__('Please enter a valid date.')
+
         ],
         'validate-date-range': [
             function (v, elm) {