upper limit fixed

Author: Morglod

build_examples/demo.js

@@ -114,7 +114,7 @@ function virtualOverflowCalcItemsV(visibleRect, itemHeight, overscanItemsCount,
     let itemStart = Math.floor(visibleRect.contentOffsetTop / itemHeight);
     let itemLen = Math.ceil(visibleRect.contentVisibleHeight / itemHeight);
     itemStart = Math.max(0, itemStart - overscanItemsCount);
-    itemLen = Math.max(0, Math.min(itemsLength, itemLen + overscanItemsCount + overscanItemsCount));
+    itemLen = Math.max(0, Math.min(itemsLength - itemStart, itemLen + overscanItemsCount + overscanItemsCount));
     return [itemStart, itemLen];
 }
 exports.virtualOverflowCalcItemsV = virtualOverflowCalcItemsV;

readme.md

@@ -35,11 +35,15 @@ function MyApp() {
         containerRef,
         itemsLength: items.length,
         itemHeight,
-        renderItem: (itemIndex, offsetTop) => (
-            <div style={{ position: "absolute", top: `${offsetTop}px` }} key={items[itemIndex]}>
-                {items[itemIndex]}
-            </div>
-        ),
+        renderItem: (itemIndex, offsetTop) => {
+            const item = items[itemIndex];
+            
+            return (
+                <div style={{ position: "absolute", top: `${offsetTop}px` }} key={item}>
+                    {item}
+                </div>
+            )
+        },
     }, []);
 
     return (

src/index.tsx

@@ -83,7 +83,7 @@ export function virtualOverflowCalcItemsV(visibleRect: VirtualOverflowVisibleRec
     let itemLen = Math.ceil(visibleRect.contentVisibleHeight / itemHeight);
 
     itemStart = Math.max(0, itemStart - overscanItemsCount);
-    itemLen = Math.max(0, Math.min(itemsLength, itemLen + overscanItemsCount + overscanItemsCount));
+    itemLen = Math.max(0, Math.min(itemsLength - itemStart, itemLen + overscanItemsCount + overscanItemsCount));
 
     return [itemStart, itemLen];
 }