refactor(frontend): scripts -> utility

packages/frontend/src/utility/get-dom-node-or-null.ts

@@ -0,0 +1,19 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+export const getNodeOrNull = (input: unknown): Node | null => {
+	if (input instanceof Node) return input;
+	return null;
+};
+
+export const getElementOrNull = (input: unknown): Element | null => {
+	if (input instanceof Element) return input;
+	return null;
+};
+
+export const getHTMLElementOrNull = (input: unknown): HTMLElement | null => {
+	if (input instanceof HTMLElement) return input;
+	return null;
+};