Add Visibility Tag Helper

VisibilityTagHelperDemo/src/VisibilityTagHelperDemo/TagHelpers/VisibilityTagHelper.cs

@@ -0,0 +1,20 @@
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Razor.TagHelpers;
+
+namespace VisibilityTagHelperDemo.TagHelpers
+{
+    [HtmlTargetElement("div")]
+    public class VisibilityTagHelper : TagHelper
+    {
+        // default to true otherwise all existing target elements will not be shown, because bool's default to false
+        public bool IsVisible { get; set; } = true;
+
+        public override Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
+        {
+            if (!IsVisible)
+                output.SuppressOutput();
+
+            return base.ProcessAsync(context, output);
+        }
+    }
+}

VisibilityTagHelperDemo/src/VisibilityTagHelperDemo/Views/Home/Index.cshtml

@@ -2,6 +2,18 @@
     ViewData["Title"] = "Home Page";
 }
 
+<div is-visible="true">
+    This should always be visible.
+</div>
+
+<div is-visible="false">
+    This should never be visible.
+</div>
+
+<div is-visible="User.Identity.IsAuthenticated">
+    This should only be visible if you're logged in.
+</div>
+
 <div id="myCarousel" class="carousel slide" data-ride="carousel" data-interval="6000">
     <ol class="carousel-indicators">
         <li data-target="#myCarousel" data-slide-to="0" class="active"></li>

VisibilityTagHelperDemo/src/VisibilityTagHelperDemo/Views/_ViewImports.cshtml

@@ -4,3 +4,4 @@
 @using VisibilityTagHelperDemo.Models.ManageViewModels
 @using Microsoft.AspNetCore.Identity
 @addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers
+@addTagHelper *, VisibilityTagHelperDemo