Refactor location validation using Haversine formula

Author: Charanjet

Client-Side Components/Client Scripts/Dynamic Location Validation Approach/User Location Validator.js

@@ -1,39 +1,52 @@
 function onSubmit() {
-  var ga = new GlideAjax('UserLocationUtils');
-  ga.addParam('sysparm_name', 'getUserLocationCoords');
-  ga.getXMLAnswer(function(response) {
-      var locData = JSON.parse(response);
-      if (!locData) {
-          g_form.addErrorMessage("No assigned location found for your profile.");
-          return false;
+  // Check if the browser supports geolocation
+  if ("geolocation" in navigator) {
+    // Request current user position
+    navigator.geolocation.getCurrentPosition(function(position) {
+      var currentLatitude = position.coords.latitude;   // Current user latitude
+      var currentLongitude = position.coords.longitude; // Current user longitude
+
+      // Allowed business location coordinates fetched from server
+      var allowedLatitude = locData.latitude;
+      var allowedLongitude = locData.longitude;
+      var locationName = locData.name;
+
+      // Earth's radius in kilometers - constant used in distance calculation formula
+      var earthRadiusKm = 6371;
+
+      // Convert degree differences to radians
+      var deltaLatitude = (currentLatitude - allowedLatitude) * Math.PI / 180;
+      var deltaLongitude = (currentLongitude - allowedLongitude) * Math.PI / 180;
+
+      // Haversine formula components
+      var a = Math.sin(deltaLatitude / 2) * Math.sin(deltaLatitude / 2) +
+              Math.cos(allowedLatitude * Math.PI / 180) *
+              Math.cos(currentLatitude * Math.PI / 180) *
+              Math.sin(deltaLongitude / 2) * Math.sin(deltaLongitude / 2);
+
+      var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
+
+      // Calculate distance in kilometers between current and allowed locations
+      var distanceKm = earthRadiusKm * c;
+
+      // Check if user's current distance exceeds tolerance (e.g., 10 km)
+      if (distanceKm > 10) {
+        alert("You are " + distanceKm.toFixed(2) + " km away from your registered location: " + locationName);
+        g_form.addErrorMessage("Location validation failed: Submission outside the allowed radius.");
+        return false; // Cancel form submission
+      } else {
+        g_form.addInfoMessage("Location validated successfully within range of " + locationName);
+        return true; // Allow form submission
       }
+    }, function(error) {
+      alert("Geolocation error: " + error.message);
+      return false; // Stop submission if geolocation fails
+    });
 
-      navigator.geolocation.getCurrentPosition(function(position) {
-          var userLat = position.coords.latitude;
-          var userLng = position.coords.longitude;
-          var allowedLat = locData.latitude;
-          var allowedLng = locData.longitude;
-          var locName = locData.name;
-
-          var R = 6371;
-          var dLat = (userLat - allowedLat) * Math.PI / 180;
-          var dLng = (userLng - allowedLng) * Math.PI / 180;
-          var a = Math.sin(dLat / 2) ** 2 +
-                  Math.cos(allowedLat * Math.PI / 180) *
-                  Math.cos(userLat * Math.PI / 180) *
-                  Math.sin(dLng / 2) ** 2;
-          var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
-          var distance = R * c;
-
-          if (distance > 10) { // 10 km tolerance
-              alert("You are " + distance.toFixed(2) + " km away from your registered office: " + locName);
-              g_form.addErrorMessage("Location validation failed.");
-              return false;
-          } else {
-              g_form.addInfoMessage("Location validated successfully within range of " + locName);
-              return true;
-          }
-      });
-  });
-  return false; // Wait for async location validation
+    // Prevent form submission while waiting for async geolocation result
+    return false;
+  } else {
+    g_form.addErrorMessage("Geolocation is not supported by your browser.");
+    return false; // Block if geolocation API unsupported
+  }
 }