Load More Button with NextJS 14 and Sanity

Google recently announced they were going to kill the infinite scroll feature on their search pages. That finally motivated to code a load more button feature for the index page. It used to load everything all at once, but now that I have a bit more content, it's good to have this feature for a better overall experience.

What needed to be done:

• Modify my getAllArticles function to accept pagination parameters
• Modify the index page to only display the first 5 articles
• Add a load more button that will be rendered client-side with the following behavior:
  • First time rendered: just show the button
  • Once pressed, render the PostLoop component with the right article and re-render the button at the bottom
  • If no more articles, display some text to tell the user you're at the bottom of the list

Code snippets

"use client";

import React, { useState } from "react";
import PostLoop from "./PostLoop";
import { getAllArticles } from "@/utils/sanity";
import { PostType } from "@/types/post";

const LoadMoreButton = () => {
  // State variables to keep track of the current page and the new page of articles
  const [currentPage, setCurrentPage] = useState<number>(3);
  const [newPage, setNewPage] = useState<PostType[]>([]);

  // Function to fetch the next page of articles when the button is clicked
  const onClick = async () => {
    // Fetch the next page of articles using the getAllArticles function
    const newPosts: PostType[] = await getAllArticles({
      page: currentPage,
      pageSize: 3,
    });

    // Append the new articles to the existing newPage array
    setNewPage([...newPage, ...newPosts]);

    // If newPosts is not empty, increment the currentPage by 1
    // Otherwise, set the currentPage to 0 to indicate that there are no more articles to load
    if (newPosts.length !== 0) {
      setCurrentPage(currentPage + 1);
    } else {
      setCurrentPage(0);
    }
  };

  return (
    <>
      {/* Render the PostLoop component with the newPage array */}
      <PostLoop posts={newPage} />

      {/* Render the load more button or the "no more articles" message based on the currentPage */}
      <div className="flex flex-col justify-center items-center">
        {currentPage !== 0 && (
          <button
            className="bg-violet-700 text-white py-2 px-4 rounded"
            onClick={onClick}
          >
            Load More Articles
          </button>
        )}
        {currentPage === 0 && (
          <h2 className="mb-2 text-2xl text-black">
            No more articles to load 😢
          </h2>
        )}
      </div>
    </>
  );
};

export default LoadMoreButton;

And the updated utility function

const getAllArticles = async ({
  page = -1,
  pageSize = 0,
}: { page?: number; pageSize?: number } = {}) => {
  let skip: number = 0;
  let filter: string = "";
  if (page > 0 && pageSize > 0) {
    skip = (page - 1) * pageSize; // Calculate the number of items to skip
    filter = `[${skip}...${skip + pageSize}]`; // Add the filter to the query
  }

  const items = await mySanityClient.fetch(
    `*[_type == "post"]{
        title,
        _id,
        _createdAt,
        publishedAt,
        description,
        body,
        mainImage,
        "slug": slug.current
    } | order(publishedAt desc)${filter}`
  );
  return items;
};