fix(ui): update viewport height without visualViewport (#1314)

* fix(ui): update viewport height without visualViewport

* fix(ui): initialize visual viewport state from helper

---------

Co-authored-by: Isaac Sanchez <isanchez-hawkins@arize.com>

packages/ui/src/hooks/useVisualViewport.test.ts

@@ -0,0 +1,35 @@
+import { describe, expect, test } from 'bun:test';
+
+import { getVisualViewportState } from './useVisualViewport';
+
+const withWindow = (value: { innerHeight: number; visualViewport?: { height: number } | null }, run: () => void) => {
+  const originalWindow = Object.getOwnPropertyDescriptor(globalThis, 'window');
+  Object.defineProperty(globalThis, 'window', {
+    configurable: true,
+    value,
+  });
+
+  try {
+    run();
+  } finally {
+    if (originalWindow) {
+      Object.defineProperty(globalThis, 'window', originalWindow);
+    } else {
+      Reflect.deleteProperty(globalThis, 'window');
+    }
+  }
+};
+
+describe('getVisualViewportState', () => {
+  test('falls back to innerHeight when visualViewport is unavailable', () => {
+    withWindow({ innerHeight: 812 }, () => {
+      expect(getVisualViewportState()).toEqual({ height: 812, keyboardHeight: 0 });
+    });
+  });
+
+  test('derives keyboard height from visualViewport height', () => {
+    withWindow({ innerHeight: 812, visualViewport: { height: 512 } }, () => {
+      expect(getVisualViewportState()).toEqual({ height: 512, keyboardHeight: 300 });
+    });
+  });
+});

packages/ui/src/hooks/useVisualViewport.ts

@@ -5,46 +5,59 @@ export interface VisualViewportState {
   keyboardHeight: number;
 }
 
-const getInitialHeight = (): number => {
+export const getVisualViewportState = (): VisualViewportState => {
-  if (typeof window === 'undefined') return 0;
+  if (typeof window === 'undefined') {
-  return window.visualViewport?.height ?? window.innerHeight;
+    return { height: 0, keyboardHeight: 0 };
+  }
+
+  const height = window.visualViewport?.height ?? window.innerHeight;
+  const keyboardHeight = window.visualViewport
+    ? Math.max(0, window.innerHeight - height)
+    : 0;
+
+  return { height, keyboardHeight };
 };
 
 export const useVisualViewport = (): VisualViewportState => {
-  const [state, setState] = React.useState<VisualViewportState>(() => ({
+  const [state, setState] = React.useState<VisualViewportState>(getVisualViewportState);
-    height: getInitialHeight(),
-    keyboardHeight: 0,
-  }));
 
   const rafIdRef = React.useRef<number | null>(null);
 
   React.useEffect(() => {
-    if (typeof window === 'undefined' || !window.visualViewport) return;
+    if (typeof window === 'undefined') return;
+
+    const visualViewport = window.visualViewport;
 
     const handleChange = () => {
       if (rafIdRef.current !== null) return;
       rafIdRef.current = requestAnimationFrame(() => {
         rafIdRef.current = null;
-        const vv = window.visualViewport!;
+        const nextState = getVisualViewportState();
-        const height = vv.height;
-        const keyboardHeight = Math.max(0, window.innerHeight - height);
         setState((prev) => {
-          if (prev.height === height && prev.keyboardHeight === keyboardHeight) return prev;
+          if (prev.height === nextState.height && prev.keyboardHeight === nextState.keyboardHeight) return prev;
-          return { height, keyboardHeight };
+          return nextState;
         });
       });
     };
 
-    window.visualViewport.addEventListener('resize', handleChange);
+    if (visualViewport) {
-    window.visualViewport.addEventListener('scroll', handleChange, { passive: true });
+      visualViewport.addEventListener('resize', handleChange);
+      visualViewport.addEventListener('scroll', handleChange, { passive: true });
+    } else {
+      window.addEventListener('resize', handleChange);
+    }
     handleChange();
 
     return () => {
       if (rafIdRef.current !== null) {
         cancelAnimationFrame(rafIdRef.current);
       }
-      window.visualViewport?.removeEventListener('resize', handleChange);
+      if (visualViewport) {
-      window.visualViewport?.removeEventListener('scroll', handleChange);
+        visualViewport.removeEventListener('resize', handleChange);
+        visualViewport.removeEventListener('scroll', handleChange);
+      } else {
+        window.removeEventListener('resize', handleChange);
+      }
     };
   }, []);