Removed a few things

Author: bvaughn

lib/core/createCachedBounds.test.ts

@@ -62,6 +62,8 @@ describe("createCachedBounds", () => {
 
     expect(cachedBounds.size).toBe(0);
 
+    expect(cachedBounds.getEstimatedSize()).toEqual(0);
+
     expect(() => {
       cachedBounds.getItemBounds(1);
     }).toThrow("Invalid index 1");

lib/core/createCachedBounds.ts

@@ -14,12 +14,13 @@ export function createCachedBounds<Props extends object>({
 
   const api = {
     getEstimatedSize() {
-      const lastBounds = cache.get(cache.size - 1);
-      if (lastBounds) {
-        return (lastBounds.scrollOffset + lastBounds.size) / cache.size;
+      if (itemCount === 0) {
+        return 0;
       } else {
-        const firstBounds = api.getItemBounds(0);
-        return firstBounds.size * itemCount;
+        const bounds = api.getItemBounds(cache.size === 0 ? 0 : cache.size - 1);
+        assert(bounds, "Unexpected bounds cache miss");
+
+        return (bounds.scrollOffset + bounds.size) / cache.size;
       }
     },
     getItemBounds(index: number) {
@@ -68,9 +69,6 @@ export function createCachedBounds<Props extends object>({
 
       return bounds;
     },
-    hasItemBounds(index: number) {
-      return cache.has(index);
-    },
     get size() {
       return cache.size;
     }

lib/core/getEstimatedSize.test.ts

@@ -21,6 +21,20 @@ describe("getEstimatedSize", () => {
       ).toBe(0);
     });
 
+    test("should return an estimate based on the first row if no sizes have yet been measured", () => {
+      expect(
+        getEstimatedSize({
+          cachedBounds: createCachedBounds({
+            itemCount: 1,
+            itemProps: EMPTY_OBJECT,
+            itemSize
+          }),
+          itemCount: 1,
+          itemSize
+        })
+      ).toBe(10);
+    });
+
     test("should return an average size based on the first item if no measurements have been taken", () => {
       expect(
         getEstimatedSize({

lib/core/getEstimatedSize.ts

@@ -1,5 +1,4 @@
 import type { CachedBounds, SizeFunction } from "./types";
-import { assert } from "../utils/assert";
 
 export function getEstimatedSize<Props extends object>({
   cachedBounds,
@@ -18,7 +17,6 @@ export function getEstimatedSize<Props extends object>({
         const bounds = cachedBounds.getItemBounds(
           cachedBounds.size === 0 ? 0 : cachedBounds.size - 1
         );
-        assert(bounds !== undefined, "Unexpected bounds cache miss");
 
         const averageItemSize =
           (bounds.scrollOffset + bounds.size) / cachedBounds.size;

lib/core/getOffsetForIndex.ts

@@ -1,5 +1,4 @@
 import type { Align } from "../types";
-import { assert } from "../utils/assert";
 import { getEstimatedSize } from "./getEstimatedSize";
 import type { CachedBounds, SizeFunction } from "./types";
 
@@ -25,12 +24,8 @@ export function getOffsetForIndex<Props extends object>({
     itemCount,
     itemSize
   });
-  if (estimatedTotalSize === undefined) {
-    return 0;
-  }
 
   const bounds = cachedBounds.getItemBounds(index);
-  assert(bounds, `Unexpected cache miss for index ${index}`);
 
   const maxOffset = Math.max(
     0,

lib/core/types.ts

@@ -6,7 +6,6 @@ export type Bounds = {
 export type CachedBounds = {
   getEstimatedSize(): number;
   getItemBounds(index: number): Bounds;
-  hasItemBounds(index: number): boolean;
   size: number;
 };