Pagination Helper

pagination.js

class PaginationHelper {
  constructor(collection, itemsPerPage) {
    this.collection = collection;
    this.itemsPerPage = itemsPerPage;
  }
  itemCount() {
    return this.collection.length;
  }
  pageCount() {
    return Math.ceil(this.itemCount() / this.itemsPerPage);
  }
  pageItemCount(pageIndex) {
    const pages = this.createPagination();
    return pages[pageIndex]?.length ?? -1;
  }
  pageIndex(itemIndex) {
    if (itemIndex < 0 || itemIndex >= this.itemCount()) {
      return -1; 
    }
    return Math.floor(itemIndex / this.itemsPerPage);
  }
  createPagination() {
    const pages = [];
    const pageCount = this.pageCount();
    const collection = [...this.collection];

    for (let i = 0; i < pageCount; i++) {
      pages.push(collection.splice(0, this.itemsPerPage));
    }

    return pages;
  }
}