Add pageCount check, add getAdjacentIndexes

src/utils/page.js

@@ -1,8 +1,10 @@
 export function getNextPageIndexLimited(currentPageIndex, pagesCount) {
+  if (pagesCount < 1) throw new Error('pagesCount must be at least 1')
   return Math.min(Math.max(currentPageIndex + 1, 0), pagesCount - 1)
 }
 
 export function getNextPageIndexInfinte(currentPageIndex, pagesCount) {
+  if (pagesCount < 1) throw new Error('pagesCount must be at least 1')
   const newCurrentPageIndex = Math.max(currentPageIndex, 0) + 1
   return newCurrentPageIndex > pagesCount - 1 ? 0 : Math.max(newCurrentPageIndex, 0)
 }
@@ -12,10 +14,12 @@ export function getNextPageIndexFn(infinite) {
 }
 
 export function getPrevPageIndexLimited(currentPageIndex, pagesCount) {
+  if (pagesCount < 1) throw new Error('pagesCount must be at least 1')
   return Math.max(Math.min(currentPageIndex - 1, pagesCount - 1), 0)
 }
 
 export function getPrevPageIndexInfinte(currentPageIndex, pagesCount) {
+  if (pagesCount < 1) throw new Error('pagesCount must be at least 1')
   const newCurrentPageIndex = Math.min(currentPageIndex, pagesCount - 1) - 1
   return newCurrentPageIndex >= 0 ? Math.min(newCurrentPageIndex, pagesCount - 1) : pagesCount - 1
 }
@@ -25,5 +29,24 @@ export function getPrevPageIndexFn(infinite) {
 }
 
 export function getPageIndex(pageIndex, pagesCount) {
+  if (pagesCount < 1) throw new Error('pagesCount must be at least 1')
   return pageIndex < 0 ? 0 : Math.min(pageIndex, pagesCount - 1)
 }
+
+export function getAdjacentIndexes(pageIndex, pagesCount, infinite) {
+  if (pagesCount < 1) throw new Error('pagesCount must be at least 1')
+  const _pageIndex = Math.max(0, Math.min(pageIndex, pagesCount - 1))
+  let rangeStart = _pageIndex - 1;
+  let rangeEnd = _pageIndex + 1;
+  rangeStart = rangeStart < 0
+    ? infinite
+      ? pagesCount - 1
+      : 0
+    : rangeStart 
+  rangeEnd = rangeEnd > pagesCount - 1
+    ? infinite
+        ? 0
+        : pagesCount - 1
+    : rangeEnd
+  return [...new Set([rangeStart, rangeEnd, _pageIndex])].sort((a, b) => a - b)
+}