Better date validation

erpnext/www/book-appointment/1.js

@@ -1,4 +1,5 @@
 
+{% include 'erpnext/public/js/date_polyfill.js' %}
 let holidays = [];
 {% if holidays %}
     holidays = {{holidays}}
@@ -9,6 +10,16 @@ function next() {
     if(holidays.includes(date)){
         frappe.throw("That day is a holiday")
     }
+    if(date === ""){
+        frappe.throw("Please select a date")
+    }
     let tz = document.getElementsByName('appointment-timezone')[0].value;
     window.location = `/book-appointment/2?date=${date}&tz=${tz}`;
+}
+
+function ondatechange(){
+    let date = document.getElementById('appointment-date')
+    if(holidays.includes(date.value)){
+        frappe.throw("That day is a holiday")
+    }
 }