refactor(frontend): scripts -> utility

packages/frontend/src/utility/device-kind.ts

@@ -0,0 +1,24 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+export type DeviceKind = 'smartphone' | 'tablet' | 'desktop';
+
+const ua = navigator.userAgent.toLowerCase();
+const isTablet = /ipad/.test(ua) || (/mobile|iphone|android/.test(ua) && window.innerWidth > 700);
+const isSmartphone = !isTablet && /mobile|iphone|android/.test(ua);
+
+export const DEFAULT_DEVICE_KIND: DeviceKind = (
+	isSmartphone
+		? 'smartphone'
+		: isTablet
+			? 'tablet'
+			: 'desktop'
+);
+
+export let deviceKind: DeviceKind = DEFAULT_DEVICE_KIND;
+
+export function updateDeviceKind(kind: DeviceKind | null) {
+	deviceKind = kind ?? DEFAULT_DEVICE_KIND;
+}