prevent blank page at the end of pagination

Author: alexcjohnson

src/dash-table/derived/data/viewport.ts

@@ -1,4 +1,5 @@
 import { memoizeOneFactory } from 'core/memoizer';
+import { lastPage } from 'dash-table/derived/paginator';
 
 import {
     Data,
@@ -13,10 +14,7 @@ function getNoPagination(data: Data, indices: Indices): IDerivedData {
 }
 
 function getFrontEndPagination(settings: IPaginationSettings, data: Data, indices: Indices): IDerivedData {
-    let currentPage = Math.min(
-        settings.current_page,
-        Math.floor(data.length / settings.page_size)
-    );
+    let currentPage = Math.min(settings.current_page, lastPage(data, settings));
 
     const firstIndex = settings.page_size * currentPage;
     const lastIndex = Math.min(

src/dash-table/derived/paginator.ts

@@ -16,6 +16,10 @@ export interface IPaginator {
     loadPrevious(): void;
 }
 
+export function lastPage(data: Data, settings: IPaginationSettings) {
+    return Math.max(Math.ceil(data.length / settings.page_size) - 1, 0);
+}
+
 function getBackEndPagination(
     pagination_settings: IPaginationSettings,
     setProps: SetProps
@@ -43,7 +47,7 @@ function getFrontEndPagination(
 ) {
     return {
         loadNext: () => {
-            let maxPageIndex = Math.floor(data.length / pagination_settings.page_size);
+            const maxPageIndex = lastPage(data, pagination_settings);
 
             if (pagination_settings.current_page >= maxPageIndex) {
                 return;