Refactor

src/core/cache.ts

@@ -1,5 +1,5 @@
 import { type InternalCacheSnapshot, type ItemsRange } from "./types";
-import { clamp, floor, max, median, min } from "./utils";
+import { clamp, floor, max, min, sort } from "./utils";
 
 type Writeable<T> = {
   -readonly [key in keyof T]: Writeable<T[key]>;
@@ -153,7 +153,6 @@ export const estimateDefaultItemSize = (
 ): number => {
   let measuredCountBeforeStart = 0;
   // This function will be called after measurement so measured size array must be longer than 0
-  const prevDefaultItemSize = cache._defaultItemSize;
   const measuredSizes: number[] = [];
   cache._sizes.forEach((s, i) => {
     if (s !== UNCACHED) {
@@ -167,9 +166,18 @@ export const estimateDefaultItemSize = (
   // Discard cache for now
   cache._computedOffsetIndex = -1;
 
+  // Calculate median
+  const sorted = sort(measuredSizes);
+  const len = sorted.length;
+  const mid = (len / 2) | 0;
+  const median =
+    len % 2 === 0 ? (sorted[mid - 1]! + sorted[mid]!) / 2 : sorted[mid]!;
+
+  const prevDefaultItemSize = cache._defaultItemSize;
+
   // Calculate diff of unmeasured items before start
   return (
-    ((cache._defaultItemSize = median(measuredSizes)) - prevDefaultItemSize) *
+    ((cache._defaultItemSize = median) - prevDefaultItemSize) *
     max(startIndex - measuredCountBeforeStart, 0)
   );
 };

src/core/utils.ts

@@ -26,17 +26,6 @@ export const sort = <T extends number>(arr: readonly T[]): T[] => {
   return [...arr].sort((a, b) => a - b);
 };
 
-/**
- * @internal
- */
-export const median = (arr: number[]): number => {
-  const sorted = sort(arr);
-  const mid = (arr.length / 2) | 0;
-  return sorted.length % 2 === 0
-    ? (sorted[mid - 1]! + sorted[mid]!) / 2
-    : sorted[mid]!;
-};
-
 /**
  * @internal
  */