flows/shell: check for elements with autofocus attribute and call .focus();

closes #76

passbook/flows/templates/flows/shell.html

@@ -120,6 +120,7 @@ const updateCard = (data) => {
             break;
         case "template":
             flowBody.innerHTML = data.body;
+            checkAutofocus();
             updateMessages();
             loadFormCode();
             setFormSubmitHandlers();
@@ -138,6 +139,12 @@ const loadFormCode = () => {
         document.head.appendChild(newScript);
     });
 };
+const checkAutofocus = () => {
+    const autofocusElement = document.querySelector("#flow-body [autofocus]");
+    if (autofocusElement !== null) {
+        autofocusElement.focus();
+    }
+};
 const updateFormAction = (form) => {
     for (let index = 0; index < form.elements.length; index++) {
         const element = form.elements[index];