refactor Static Blazor script processing

Oqtane.Server/wwwroot/js/reload.js

@@ -0,0 +1,87 @@
+const scriptInfoBySrc = new Map();
+
+function getKey(script) {
+    if (script.hasAttribute("src") && script.src !== "") {
+        return script.src;
+    } else {
+        return script.innerHTML;
+    }
+}
+
+export function onUpdate() {
+    let timestamp = Date.now();
+    let enhancedNavigation = scriptInfoBySrc.size !== 0;
+
+    // iterate over all script elements in page
+    const scripts = document.getElementsByTagName("script");
+    for (const script of scripts) {
+        let key = getKey(script);
+        let scriptInfo = scriptInfoBySrc.get(key);
+        if (!scriptInfo) {
+            // new script added
+            scriptInfo = { timestamp: timestamp };
+            scriptInfoBySrc.set(key, scriptInfo);
+            if (enhancedNavigation) {
+                reloadScript(script);
+            }
+        } else {
+            // existing script
+            scriptInfo.timestamp = timestamp;
+            if (script.hasAttribute("data-reload") && script.getAttribute("data-reload") === "true") {
+                reloadScript(script);
+            }
+        }
+    }
+
+    // remove scripts that are no longer referenced
+    for (const [key, scriptInfo] of scriptInfoBySrc) {
+        if (scriptInfo.timestamp !== timestamp) {
+            scriptInfoBySrc.delete(key);
+        }
+    }
+}
+
+function reloadScript(script) {
+    try {
+        replaceScript(script);
+    } catch (error) {
+        if (script.hasAttribute("src") && script.src !== "") {
+            console.error("Failed to load external script: ${script.src}", error);
+        } else {
+            console.error("Failed to load inline script: ${script.innerHtml}", error);
+        }
+    }
+}
+
+function replaceScript(script) {
+    return new Promise((resolve, reject) => {
+        var newScript = document.createElement("script");
+
+        newScript.async = false;
+        if (script.type !== "") {
+            newScript.type = script.type;
+        }
+
+        if (script.src !== "") {
+            newScript.src = script.src;
+            if (script.integrity !== "") {
+                newScript.integrity = script.integrity;
+            }
+            if (script.crossorigin !== "") {
+                newScript.crossOrigin = script.crossOrigin;
+            }
+        } else {
+            newScript.innerHTML = script.innerHTML;
+        }
+
+        newScript.onload = () => resolve();
+        newScript.onerror = (error) => reject(error);
+
+        // remove existing newScript script
+        script.remove();
+
+        // replace with new newScript to force reload in Blazor
+        document.head.appendChild(newScript);
+    });
+}
+