# Why does this pagination helper skip an item between pages?

**URL:** <https://forum.kirupa.com/t/why-does-this-pagination-helper-skip-an-item-between-pages/680158>\
**Category:** web dev\
**Created:** [April 7, 2026, 3:00pm UTC](https://forum.kirupa.com/t/why-does-this-pagination-helper-skip-an-item-between-pages/680158 "2026-04-07T15:00:12Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Yoshiii](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.kirupa.com/yoshiii/32/31156_2.png) [@Yoshiii](https://forum.kirupa.com/u/Yoshiii)\
**Post date:** [April 7, 2026, 3:00pm UTC](https://forum.kirupa.com/t/why-does-this-pagination-helper-skip-an-item-between-pages/680158/1 "2026-04-07T15:00:12Z")

</div>

Hey folks, I’m wiring up a tiny client-side pagination helper for a search results panel, and I’m trying to keep it simple without duplicating items or dropping one when the page size changes.

```js
function getPage(items, page, pageSize) {
  const start = page * pageSize;
  const end = start + pageSize;
  return items.slice(start, end);
}

const items = ["a", "b", "c", "d", "e", "f", "g"];
console.log(getPage(items, 1, 3));
console.log(getPage(items, 2, 2));

```

Why does this kind of page math feel fine at first but then skip an item across views, and what index logic should I use if page numbers in my UI are meant to start at 1?

Yoshiii

---

<div class="post-metadata">

**Author:** ![WaffleFries](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.kirupa.com/wafflefries/32/31185_2.png) [@WaffleFries](https://forum.kirupa.com/u/WaffleFries)\
**Post date:** [April 7, 2026, 3:35pm UTC](https://forum.kirupa.com/t/why-does-this-pagination-helper-skip-an-item-between-pages/680158/2 "2026-04-07T15:35:31Z")

</div>

@Yoshiii yup, the bug is just that your helper is using zero-based page math while your UI is one-based. If page 1 in the UI should start at index 0, the start index needs to be `(page - 1) * pageSize`.

```auto

js
function getPage(items, page, pageSize) {
  const start = (page - 1) * pageSize;
  return items.slice(start, start + pageSize);
}

```

Concrete example with your array: page 1, size 3 gives `["a", "b", "c"]`, but page 2, size 2 gives `["c", "d"]` because changing the page size changes where that page number lands. So if `pageSize` changes, reset to page 1 or keep an absolute item offset instead of reusing the old page number.

WaffleFries