diff --git a/src/OrchardCore.Modules/OrchardCore.Rules/Drivers/JavascriptConditionDisplayDriver.cs b/src/OrchardCore.Modules/OrchardCore.Rules/Drivers/JavascriptConditionDisplayDriver.cs
index 92b439af998..ec85a37b5db 100644
--- a/src/OrchardCore.Modules/OrchardCore.Rules/Drivers/JavascriptConditionDisplayDriver.cs
+++ b/src/OrchardCore.Modules/OrchardCore.Rules/Drivers/JavascriptConditionDisplayDriver.cs
@@ -1,14 +1,39 @@
+using System;
 using System.Threading.Tasks;
+using Esprima;
+using Jint.Runtime;
+using Microsoft.AspNetCore.Mvc.Localization;
+using Microsoft.Extensions.Localization;
 using OrchardCore.DisplayManagement.Handlers;
 using OrchardCore.DisplayManagement.ModelBinding;
+using OrchardCore.DisplayManagement.Notify;
 using OrchardCore.DisplayManagement.Views;
+using OrchardCore.Mvc.ModelBinding;
 using OrchardCore.Rules.Models;
+using OrchardCore.Rules.Services;
 using OrchardCore.Rules.ViewModels;
 
 namespace OrchardCore.Rules.Drivers
 {
     public class JavascriptConditionDisplayDriver : DisplayDriver<Condition, JavascriptCondition>
     {
+        private readonly IHtmlLocalizer H;
+        private readonly IStringLocalizer S;
+        private readonly INotifier _notifier;
+        private readonly JavascriptConditionEvaluator _evaluator;
+
+        public JavascriptConditionDisplayDriver(
+            IHtmlLocalizer<JavascriptConditionDisplayDriver> htmlLocalizer,
+            IStringLocalizer<JavascriptConditionDisplayDriver> stringLocalizer,
+            JavascriptConditionEvaluator evaluator,
+            INotifier notifier)
+        {
+            H = htmlLocalizer;
+            S = stringLocalizer;
+            _evaluator = evaluator;
+            _notifier = notifier;
+        }
+
         public override IDisplayResult Display(JavascriptCondition condition)
         {
             return
@@ -32,8 +57,40 @@ public override async Task<IDisplayResult> UpdateAsync(JavascriptCondition condi
             var model = new JavascriptConditionViewModel();
             await updater.TryUpdateModelAsync(model, Prefix);
 
-            // TODO is empty.
-            condition.Script = model.Script;
+            // CodeMirror hides the textarea which displays the error when updater.ModelState.AddModelError() is used,
+            // that's why a notifier is used to show validation errors.
+            if (string.IsNullOrWhiteSpace(model.Script))
+            {
+                updater.ModelState.AddModelError(Prefix, nameof(model.Script), S["Please provide a script."]);
+                await _notifier.ErrorAsync(H["Please provide a script."]);
+                return Edit(condition);
+            }
+
+            try
+            {
+                _ = await _evaluator.EvaluateAsync(new()
+                {
+                    ConditionId = condition.ConditionId,
+                    Name = condition.Name,
+                    Script = model.Script
+                });
+                condition.Script = model.Script;
+            }
+            catch (ParserException ex) // Invalid syntax
+            {
+                updater.ModelState.AddModelError(Prefix, nameof(model.Script), S["The script couldn't be parsed. Details: {0}", ex.Message]);
+                await _notifier.ErrorAsync(H["The script couldn't be parsed. Details: {0}", ex.Message]);
+            }
+            catch (JavaScriptException ex) // Evaluation threw an Error
+            {
+                updater.ModelState.AddModelError(Prefix, nameof(model.Script), S["JavaScript evaluation resulted in an exception. Details: {0}", ex.Message]);
+                await _notifier.ErrorAsync(H["JavaScript evaluation resulted in an exception. Details: {0}", ex.Message]);
+            }
+            catch (Exception ex) when (ex is InvalidCastException or FormatException) // Evaluation completes successfully, but the result cannot be converted to Boolean
+            {
+                updater.ModelState.AddModelError(Prefix, nameof(model.Script), S["The script evaluation failed. Details: {0}", ex.Message]);
+                await _notifier.ErrorAsync(H["The script evaluation failed. Details: {0}", ex.Message]);
+            }
 
             return Edit(condition);
         }
diff --git a/src/OrchardCore.Modules/OrchardCore.Rules/OrchardCore.Rules.csproj b/src/OrchardCore.Modules/OrchardCore.Rules/OrchardCore.Rules.csproj
index 5ec2e46ac53..826283775c7 100644
--- a/src/OrchardCore.Modules/OrchardCore.Rules/OrchardCore.Rules.csproj
+++ b/src/OrchardCore.Modules/OrchardCore.Rules/OrchardCore.Rules.csproj
@@ -14,6 +14,10 @@
     <FrameworkReference Include="Microsoft.AspNetCore.App" />
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Jint" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\..\OrchardCore\OrchardCore.ContentManagement.Display\OrchardCore.ContentManagement.Display.csproj" />
     <ProjectReference Include="..\..\OrchardCore\OrchardCore.DisplayManagement\OrchardCore.DisplayManagement.csproj" />