fix(table-core): skip state update in toggleExpanded when state is unchanged

.changeset/fix-toggle-expanded-noop.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/table-core': patch
+---
+
+Skip state update in toggleExpanded when the desired state matches the current state, avoiding unnecessary re-renders

packages/table-core/src/features/RowExpanding.ts

@@ -290,9 +290,16 @@ export const RowExpanding: TableFeature = {
     table: Table<TData>,
   ): void => {
     row.toggleExpanded = (expanded) => {
-      table.setExpanded((old) => {
-        const exists = old === true ? true : !!old?.[row.id]
+      const isCurrentlyExpanded = row.getIsExpanded()
+      const newExpanded = expanded ?? !isCurrentlyExpanded
+
+      // If the desired state matches the current state, skip the update
+      // to avoid unnecessary re-renders
+      if (newExpanded === isCurrentlyExpanded) {
+        return
+      }
 
+      table.setExpanded((old) => {
         let oldExpanded: ExpandedStateList = {}
 
         if (old === true) {
@@ -303,21 +310,15 @@ export const RowExpanding: TableFeature = {
           oldExpanded = old
         }
 
-        expanded = expanded ?? !exists
-
-        if (!exists && expanded) {
+        if (newExpanded) {
           return {
             ...oldExpanded,
             [row.id]: true,
           }
         }
 
-        if (exists && !expanded) {
-          const { [row.id]: _, ...rest } = oldExpanded
-          return rest
-        }
-
-        return old
+        const { [row.id]: _, ...rest } = oldExpanded
+        return rest
       })
     }
     row.getIsExpanded = () => {