Introduce groups for preloading

Author: maraf

src/Components/Endpoints/src/Rendering/EndpointHtmlRenderer.Streaming.cs

@@ -332,13 +332,13 @@ private void AppendWebAssemblyPreloadHeaders()
                     continue;
                 }
 
-                // Use preloadrel to identify assets that should to be preloaded
+                // Use preloadgroup=webassembly to identify assets that should to be preloaded
                 string? header = null;
                 foreach (var property in asset.Properties)
                 {
-                    if (property.Name.Equals("preloadrel", StringComparison.OrdinalIgnoreCase))
+                    if (property.Name.Equals("preloadgroup", StringComparison.OrdinalIgnoreCase) && property.Value.Equals("webassembly", StringComparison.OrdinalIgnoreCase))
                     {
-                        header = String.Concat($"<{asset.Url}>", "; rel=", property.Value);
+                        header = $"<{asset.Url}>";
                         break;
                     }
                 }
@@ -351,7 +351,11 @@ private void AppendWebAssemblyPreloadHeaders()
                 string? order = null;
                 foreach (var property in asset.Properties)
                 {
-                    if (property.Name.Equals("preloadas", StringComparison.OrdinalIgnoreCase))
+                    if (property.Name.Equals("preloadrel", StringComparison.OrdinalIgnoreCase))
+                    {
+                        header = String.Concat(header, "; rel=", property.Value);
+                    }
+                    else if (property.Name.Equals("preloadas", StringComparison.OrdinalIgnoreCase))
                     {
                         header = String.Concat(header, "; as=", property.Value);
                     }

src/Components/Endpoints/test/EndpointHtmlRendererTest.cs

@@ -88,15 +88,26 @@ public async Task CanPreload_WebAssembly_ResourceAssets()
                             new ResourceAssetProperty("preloadpriority", "high"),
                             new ResourceAssetProperty("preloadcrossorigin", "anonymous"),
                             new ResourceAssetProperty("integrity", "abcd"),
-                            new ResourceAssetProperty("preloadorder", "2")
+                            new ResourceAssetProperty("preloadorder", "2"),
+                            new ResourceAssetProperty("preloadgroup", "webassembly")
                         ]),
                         new ResourceAsset("first.js", [
                             new ResourceAssetProperty("preloadrel", "preload"),
                             new ResourceAssetProperty("preloadas", "script"),
                             new ResourceAssetProperty("preloadpriority", "high"),
                             new ResourceAssetProperty("preloadcrossorigin", "anonymous"),
                             new ResourceAssetProperty("integrity", "abcd"),
-                            new ResourceAssetProperty("preloadorder", "1")
+                            new ResourceAssetProperty("preloadorder", "1"),
+                            new ResourceAssetProperty("preloadgroup", "webassembly")
+                        ]),
+                        new ResourceAsset("preload-nowebassembly.js", [
+                            new ResourceAssetProperty("preloadrel", "preload"),
+                            new ResourceAssetProperty("preloadas", "script"),
+                            new ResourceAssetProperty("preloadpriority", "high"),
+                            new ResourceAssetProperty("preloadcrossorigin", "anonymous"),
+                            new ResourceAssetProperty("integrity", "abcd"),
+                            new ResourceAssetProperty("preloadorder", "1"),
+                            new ResourceAssetProperty("preloadgroup", "abcd")
                         ]),
                         new ResourceAsset("nopreload.js", [
                             new ResourceAssetProperty("integrity", "abcd")

src/Shared/Components/ResourceCollectionResolver.cs

@@ -47,6 +47,7 @@ public ResourceAssetCollection ResolveResourceCollection()
             string? preloadPriority = null;
             string? preloadCrossorigin = null;
             string? preloadOrder = null;
+            string? preloadGroup = null;
 #else
             string label = null;
             string integrity = null;
@@ -55,6 +56,7 @@ public ResourceAssetCollection ResolveResourceCollection()
             string preloadPriority = null;
             string preloadCrossorigin = null;
             string preloadOrder = null;
+            string preloadGroup = null;
 #endif
 
             // If there's a selector this means that this is an alternative representation for a resource, so skip it.
@@ -99,9 +101,14 @@ public ResourceAssetCollection ResolveResourceCollection()
                         preloadOrder = property.Value;
                         foundProperties++;
                     }
+                    else if (property.Name.Equals("preloadgroup", StringComparison.OrdinalIgnoreCase))
+                    {
+                        preloadGroup = property.Value;
+                        foundProperties++;
+                    }
                 }
 
-                AddResource(resources, descriptor, label, integrity, preloadRel, preloadAs, preloadPriority, preloadCrossorigin, preloadOrder, foundProperties);
+                AddResource(resources, descriptor, label, integrity, preloadRel, preloadAs, preloadPriority, preloadCrossorigin, preloadOrder, preloadGroup, foundProperties);
             }
         }
 
@@ -136,6 +143,7 @@ private static void AddResource(
         string? preloadPriority,
         string? preloadCrossorigin,
         string? preloadOrder,
+        string? preloadGroup,
 #else
         string label,
         string integrity,
@@ -144,6 +152,7 @@ private static void AddResource(
         string preloadPriority,
         string preloadCrossorigin,
         string preloadOrder,
+        string preloadGroup,
 #endif
     int foundProperties)
     {
@@ -179,6 +188,10 @@ private static void AddResource(
             {
                 properties[index++] = new ResourceAssetProperty("preloadorder", preloadOrder);
             }
+            if (preloadGroup != null)
+            {
+                properties[index++] = new ResourceAssetProperty("preloadgroup", preloadGroup);
+            }
 
             resources.Add(new ResourceAsset(descriptor.Route, properties));
         }