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website/node_modules/@mui/x-internals/domUtils/isHTMLElement.mjs

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+import ownerWindow from '@mui/utils/ownerWindow';
+
+/**
+ * Checks if a value is an HTMLElement, including elements from other iframes/realms.
+ */
+export function isHTMLElement(value) {
+  if (typeof window === 'undefined' || value == null) {
+    return false;
+  }
+  if (value instanceof HTMLElement) {
+    return true;
+  }
+  // Cross-realm: must be an element node (nodeType 1) from another window.
+  // The try/catch guards against detached/destroyed windows where accessing
+  // `.HTMLElement` on the owner window may throw.
+  try {
+    return value.nodeType === 1 && value instanceof ownerWindow(value).HTMLElement;
+  } catch {
+    return false;
+  }
+}