1 files changed, 83 insertions, 0 deletions

diff --git a/Blog/wwwroot/Blog.lib.module.js b/Blog/wwwroot/Blog.lib.module.js
new file mode 100644
index 0000000..c1a5870
--- /dev/null
+++ b/Blog/wwwroot/Blog.lib.module.js
@@ -0,0 +1,83 @@
+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 (src.startsWith("./")) {
+        src = new URL(src.substr(2), document.baseURI).toString();
+    }
+
+    const module = await import(src);
+
+    if (pageScriptInfo.referenceCount <= 0) {
+        return;
+    }
+
+    pageScriptInfo.module = module;
+    module.onLoad?.();
+    module.onUpdate?.();
+}
+
+function onEnhancedLoad() {
+    for (const [src, { module, referenceCount }] of pageScriptInfoBySrc) {
+        if (referenceCount <= 0) {
+            module?.onDispose?.();
+            pageScriptInfoBySrc.delete(src);
+        }
+    }
+
+    for (const { module } of pageScriptInfoBySrc.values()) {
+        module?.onUpdate?.();
+    }
+}
+
+export function afterWebStarted(blazor) {
+    console.log("afterWebStarted");
+    customElements.define('page-script', class extends HTMLElement {
+        static observedAttributes = ['src'];
+
+        attributeChangedCallback(name, oldValue, newValue) {
+            if (name !== 'src') {
+                return;
+            }
+
+            this.src = newValue;
+            unregisterPageScriptElement(oldValue);
+            registerPageScriptElement(newValue);
+        }
+
+        disconnectedCallback() {
+            unregisterPageScriptElement(this.src);
+        }
+    });
+
+    blazor.addEventListener('enhancedload', onEnhancedLoad);
+}
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