easyLogic ErrorsJavaScript

The off-by-one pagination

An AI assistant wrote a pagination helper function to extract a specific page of items from a list. It was asked to return items for page 1, page 2, etc. (where pages are 1-indexed, and each page has a size of `limit`). However, the output is incorrect. Why?

paginate.js

function getPaginatedItems(items, page, limit) {
  const startIndex = page * limit;
  const endIndex = startIndex + limit;
  return items.slice(startIndex, endIndex);
}

What is the logic error in calculating the pagination indexes?

The startIndex is offset; for page 1, it starts at limit instead of 0.

Array.slice is destructive and will mutate the original items array.

The endIndex should be startIndex + limit - 1 because slice is inclusive of the end boundary.

The page variable must be converted to a string before arithmetic operations.