From e43e03e500588b2da36f184ecaba2b8e5a506596 Mon Sep 17 00:00:00 2001
From: Damian Pieczynski <piecyk@gmail.com>
Date: Tue, 3 Oct 2023 22:30:00 +0200
Subject: [PATCH] fix: prevent returning items when container size is zero
 (#598)

---
 examples/react/dynamic/src/main.tsx             |  4 ++--
 packages/react-virtual/__tests__/index.test.tsx |  2 +-
 packages/virtual-core/__tests__/index.test.ts   | 12 ++++++++++++
 packages/virtual-core/src/index.ts              | 15 +++++++++------
 4 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/examples/react/dynamic/src/main.tsx b/examples/react/dynamic/src/main.tsx
index 1b765bc4..6539b485 100644
--- a/examples/react/dynamic/src/main.tsx
+++ b/examples/react/dynamic/src/main.tsx
@@ -74,7 +74,7 @@ function RowVirtualizerDynamic() {
               top: 0,
               left: 0,
               width: '100%',
-              transform: `translateY(${items[0].start}px)`,
+              transform: `translateY(${items[0]?.start ?? 0}px)`,
             }}
           >
             {items.map((virtualRow) => (
@@ -131,7 +131,7 @@ const RowVirtualizerDynamicWindow = () => {
             left: 0,
             width: '100%',
             transform: `translateY(${
-              items[0].start - virtualizer.options.scrollMargin
+              items[0] ? items[0].start - virtualizer.options.scrollMargin : 0
             }px)`,
           }}
         >
diff --git a/packages/react-virtual/__tests__/index.test.tsx b/packages/react-virtual/__tests__/index.test.tsx
index b85dae62..6455fdf3 100644
--- a/packages/react-virtual/__tests__/index.test.tsx
+++ b/packages/react-virtual/__tests__/index.test.tsx
@@ -148,7 +148,7 @@ test('should render given dynamic size after scroll', () => {
   expect(screen.queryByText('Row 6')).toBeInTheDocument()
   expect(screen.queryByText('Row 7')).not.toBeInTheDocument()
 
-  expect(renderer).toHaveBeenCalledTimes(3)
+  expect(renderer).toHaveBeenCalledTimes(2)
 })
 
 test('should use rangeExtractor', () => {
diff --git a/packages/virtual-core/__tests__/index.test.ts b/packages/virtual-core/__tests__/index.test.ts
index 8607c68c..9a1126f4 100644
--- a/packages/virtual-core/__tests__/index.test.ts
+++ b/packages/virtual-core/__tests__/index.test.ts
@@ -3,3 +3,15 @@ import { Virtualizer } from '../src/index'
 test('should export the Virtualizer class', () => {
   expect(Virtualizer).toBeDefined()
 })
+
+test('shoul', () => {
+  const virtualizer = new Virtualizer({
+    count: 100,
+    getScrollElement: () => null,
+    estimateSize: () => 50,
+    scrollToFn: jest.fn(),
+    observeElementRect: jest.fn(),
+    observeElementOffset: jest.fn(),
+  })
+  expect(virtualizer.getVirtualItems()).toEqual([])
+})
diff --git a/packages/virtual-core/src/index.ts b/packages/virtual-core/src/index.ts
index 3ac1069d..e60a2910 100644
--- a/packages/virtual-core/src/index.ts
+++ b/packages/virtual-core/src/index.ts
@@ -587,13 +587,16 @@ export class Virtualizer<
       this.calculateRange(),
       this.options.overscan,
       this.options.count,
+      this.getSize(),
     ],
-    (rangeExtractor, range, overscan, count) => {
-      return rangeExtractor({
-        ...range,
-        overscan,
-        count,
-      })
+    (rangeExtractor, range, overscan, count, outerSize) => {
+      return outerSize === 0
+        ? []
+        : rangeExtractor({
+            ...range,
+            overscan,
+            count,
+          })
     },
     {
       key: process.env.NODE_ENV !== 'production' && 'getIndexes',