Exclude blank fields

src/registrar/assets/js/get-gov.js

@@ -134,10 +134,19 @@ function _checkDomainAvailability(el) {
   const callback = (response) => {
     toggleInputValidity(el, (response && response.available), msg=response.message);
     announce(el.id, response.message);
+
+    // Determines if we ignore the field if it is just blank
+    ignore_blank = el.classList.contains("blank-ok")
     if (el.validity.valid) {
       el.classList.add('usa-input--success');
       // use of `parentElement` due to .gov inputs being wrapped in www/.gov decoration
       inlineToast(el.parentElement, el.id, SUCCESS, response.message);
+    } else if (ignore_blank && response.code == "required"){
+      // Visually remove the error
+      error = "usa-input--error"
+      if (el.classList.contains(error)){
+        el.classList.remove(error)
+      }
     } else {
       inlineToast(el.parentElement, el.id, ERROR, response.message);
     }

src/registrar/templates/application_dotgov_domain.html

@@ -73,9 +73,11 @@
       {# attr_validate / validate="domain" invokes code in get-gov.js #}
       {# attr_auto_validate likewise triggers behavior in get-gov.js #}
       {% with append_gov=True attr_validate="domain" attr_auto_validate=True %}
-        {% for form in forms.1 %}
+        {% with add_class="blank-ok" %}
-          {% input_with_errors form.alternative_domain %}
+          {% for form in forms.1 %}
-        {% endfor %}
+            {% input_with_errors form.alternative_domain %}
+          {% endfor %}
+        {% endwith %}
       {% endwith %}
     {% endwith %}