add ability to reload JavaScript on page transitions with enhanced navigation

Oqtane.Client/UI/SiteRouter.razor

@@ -580,6 +580,7 @@
                             ES6Module = resource.ES6Module,
                             Content = resource.Content,
                             RenderMode = resource.RenderMode,
+                            Reload = resource.Reload,
                             Level = level,
                             Namespace = name
                         });

Oqtane.Server/Components/App.razor

@@ -526,12 +526,20 @@
     {
         if (!string.IsNullOrEmpty(resource.Url))
         {
-            var url = (resource.Url.Contains("://")) ? resource.Url : alias.BaseUrl + resource.Url;
-            return "<script" +
-                ((!string.IsNullOrEmpty(resource.Integrity)) ? " integrity=\"" + resource.Integrity + "\"" : "") +
-                ((!string.IsNullOrEmpty(resource.CrossOrigin)) ? " crossorigin=\"" + resource.CrossOrigin + "\"" : "") +
-                ((resource.ES6Module) ? " type=\"module\"" : "") +
-                " src =\"" + url + "\"></script>"; // src at end of element due to enhanced navigation patch algorithm
+            if (!resource.Reload)
+            {
+                var url = (resource.Url.Contains("://")) ? resource.Url : alias.BaseUrl + resource.Url;
+                return "<script" +
+                    ((!string.IsNullOrEmpty(resource.Integrity)) ? " integrity=\"" + resource.Integrity + "\"" : "") +
+                    ((!string.IsNullOrEmpty(resource.CrossOrigin)) ? " crossorigin=\"" + resource.CrossOrigin + "\"" : "") +
+                    ((resource.ES6Module) ? " type=\"module\"" : "") +
+                    " src =\"" + url + "\"></script>"; // src at end of element due to enhanced navigation patch algorithm
+            }
+            else
+            {
+                // use custom element which can execute script on every page transition
+                return "<page-script src=\"" + resource.Url + "\"></page-script>";
+            }
         }
         else
         {
@@ -684,6 +692,7 @@
                         ES6Module = resource.ES6Module,
                         Content = resource.Content,
                         RenderMode = resource.RenderMode,
+                        Reload = resource.Reload,
                         Level = level,
                         Namespace = name
                     });

Oqtane.Server/wwwroot/Oqtane.Server.lib.module.js

@@ -0,0 +1,90 @@
+const pageScriptInfoBySrc = new Map();
+
+function registerPageScriptElement(src) {
+    if (!src) {
+        throw new Error('Must provide a non-empty value for the "src" attribute.');
+    }
+
+    let pageScriptInfo = pageScriptInfoBySrc.get(src);
+
+    if (pageScriptInfo) {
+        pageScriptInfo.referenceCount++;
+    } else {
+        pageScriptInfo = { referenceCount: 1, module: null };
+        pageScriptInfoBySrc.set(src, pageScriptInfo);
+        initializePageScriptModule(src, pageScriptInfo);
+    }
+}
+
+function unregisterPageScriptElement(src) {
+    if (!src) {
+        return;
+    }
+
+    const pageScriptInfo = pageScriptInfoBySrc.get(src);
+    if (!pageScriptInfo) {
+        return;
+    }
+
+    pageScriptInfo.referenceCount--;
+}
+
+async function initializePageScriptModule(src, pageScriptInfo) {
+    // If the path is relative, normalize it by by making it an absolute URL
+    // with document's the base HREF.
+    if (src.startsWith("./")) {
+        src = new URL(src.substr(2), document.baseURI).toString();
+    }
+
+    const module = await import(src);
+
+    if (pageScriptInfo.referenceCount <= 0) {
+        // All page-script elements with the same 'src' were
+        // unregistered while we were loading the module.
+        return;
+    }
+
+    pageScriptInfo.module = module;
+    module.onLoad?.();
+    module.onUpdate?.();
+}
+
+function onEnhancedLoad() {
+    // Start by invoking 'onDispose' on any modules that are no longer referenced.
+    for (const [src, { module, referenceCount }] of pageScriptInfoBySrc) {
+        if (referenceCount <= 0) {
+            module?.onDispose?.();
+            pageScriptInfoBySrc.delete(src);
+        }
+    }
+
+    // Then invoke 'onUpdate' on the remaining modules.
+    for (const { module } of pageScriptInfoBySrc.values()) {
+        module?.onUpdate?.();
+    }
+}
+
+export function afterWebStarted(blazor) {
+    customElements.define('page-script', class extends HTMLElement {
+        static observedAttributes = ['src'];
+
+        // We use attributeChangedCallback instead of connectedCallback
+        // because a page-script element might get reused between enhanced
+        // navigations.
+        attributeChangedCallback(name, oldValue, newValue) {
+            if (name !== 'src') {
+                return;
+            }
+
+            this.src = newValue;
+            unregisterPageScriptElement(oldValue);
+            registerPageScriptElement(newValue);
+        }
+
+        disconnectedCallback() {
+            unregisterPageScriptElement(this.src);
+        }
+    });
+
+    blazor.addEventListener('enhancedload', onEnhancedLoad);
+}

Oqtane.Shared/Models/Resource.cs

@@ -67,6 +67,11 @@ public string Url
         /// </summary>
         public string RenderMode { get; set; }
 
+        /// <summary>
+        /// Indicates that a script should be reloaded on every page transition - not applicable to Stylesheets
+        /// </summary>
+        public bool Reload { get; set; }
+
         /// <summary>
         /// The namespace of the component that declared the resource - only used in SiteRouter
         /// </summary>