Page indexing

indexing.js

const filterPostsByPageIndex = (posts, pageIndex) => {
  const postPerPage = 5;
  // get the total posts from page 1 to current page
  const totalPagePosts = pageIndex * postPerPage;

  // get the total posts from page 1 to previous page
  const prevPagePosts = totalPagePosts - postPerPage;

  return posts.filter(
    (post, index) => index < totalPagePosts && index >= prevPagePosts
  );
};