refactor: unify align handling with switch statement

Move nearest logic into switch for consistent code style.
Also extract static ALIGN_MAP constant in BodyGrid.tsx.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: 刘欢

src/Table.tsx

@@ -369,29 +369,34 @@ const Table = <RecordType extends DefaultRecordType>(
                 const elementTop = (targetElement as HTMLElement).offsetTop;
                 const elementHeight = (targetElement as HTMLElement).offsetHeight;
                 const containerHeight = container.clientHeight;
-                const currentTop = container.scrollTop;
                 const elementBottom = elementTop + elementHeight;
-                const viewportBottom = currentTop + containerHeight;
                 let targetTop: number;
 
-                if (align === 'nearest') {
-                  const targetWithOffset = elementTop + offset;
-                  const targetBottomWithOffset = elementBottom + offset;
-
-                  if (targetWithOffset < currentTop) {
-                    targetTop = targetWithOffset;
-                  } else if (targetBottomWithOffset > viewportBottom) {
-                    targetTop = targetBottomWithOffset - containerHeight;
-                  } else {
-                    targetTop = currentTop;
+                switch (align) {
+                  case 'nearest': {
+                    const currentTop = container.scrollTop;
+                    const viewportBottom = currentTop + containerHeight;
+                    const targetWithOffset = elementTop + offset;
+                    const targetBottomWithOffset = elementBottom + offset;
+
+                    if (targetWithOffset < currentTop) {
+                      targetTop = targetWithOffset;
+                    } else if (targetBottomWithOffset > viewportBottom) {
+                      targetTop = targetBottomWithOffset - containerHeight;
+                    } else {
+                      targetTop = currentTop;
+                    }
+                    break;
                   }
-                } else {
-                  const alignMap: Record<string, number> = {
-                    start: elementTop,
-                    end: elementBottom - containerHeight,
-                    center: elementTop - (containerHeight - elementHeight) / 2,
-                  };
-                  targetTop = alignMap[align ?? 'start'] + offset;
+                  case 'end':
+                    targetTop = elementBottom - containerHeight + offset;
+                    break;
+                  case 'center':
+                    targetTop = elementTop - (containerHeight - elementHeight) / 2 + offset;
+                    break;
+                  case 'start':
+                  default:
+                    targetTop = elementTop + offset;
                 }
 
                 container.scrollTo({ top: targetTop });

src/VirtualTable/BodyGrid.tsx

@@ -12,6 +12,12 @@ import type {
 import BodyLine from './BodyLine';
 import { GridContext, StaticContext } from './context';
 
+const ALIGN_MAP: Record<string, 'top' | 'bottom' | 'auto'> = {
+  start: 'top',
+  end: 'bottom',
+  nearest: 'auto',
+};
+
 export interface GridProps<RecordType = any> {
   data: RecordType[];
   onScroll: OnCustomizeScroll;
@@ -87,13 +93,7 @@ const Grid = React.forwardRef<GridRef, GridProps>((props, ref) => {
       scrollTo: (config: VirtualScrollConfig) => {
         const { align, offset, ...restConfig } = config;
 
-        const alignMap: Record<string, 'top' | 'bottom' | 'auto'> = {
-          start: 'top',
-          end: 'bottom',
-          nearest: 'auto',
-        };
-
-        const virtualAlign = alignMap[align] ?? (offset ? 'top' : 'auto');
+        const virtualAlign = ALIGN_MAP[align] ?? (offset ? 'top' : 'auto');
 
         listRef.current?.scrollTo({
           ...restConfig,