add Greeting modal component

hyperglass/ui/hooks/useSessionStorage.js

@@ -0,0 +1,47 @@
+/*
+react-use: useSessionStorage
+https://github.com/streamich/react-use/blob/master/src/useSessionStorage.ts
+*/
+
+import { useEffect, useState } from "react";
+
+const useSessionStorage = (key, initialValue, raw) => {
+    const isClient = typeof window === "object";
+    if (!isClient) {
+        return [initialValue, () => {}];
+    }
+
+    const [state, setState] = useState(() => {
+        try {
+            const sessionStorageValue = sessionStorage.getItem(key);
+            if (typeof sessionStorageValue !== "string") {
+                sessionStorage.setItem(
+                    key,
+                    raw ? String(initialValue) : JSON.stringify(initialValue)
+                );
+                return initialValue;
+            } else {
+                return raw ? sessionStorageValue : JSON.parse(sessionStorageValue || "null");
+            }
+        } catch {
+            // If user is in private mode or has storage restriction
+            // sessionStorage can throw. JSON.parse and JSON.stringify
+            // cat throw, too.
+            return initialValue;
+        }
+    });
+
+    useEffect(() => {
+        try {
+            const serializedState = raw ? String(state) : JSON.stringify(state);
+            sessionStorage.setItem(key, serializedState);
+        } catch {
+            // If user is in private mode or has storage restriction
+            // sessionStorage can throw. Also JSON.stringify can throw.
+        }
+    });
+
+    return [state, setState];
+};
+
+export default useSessionStorage;