Add an infinite scroll example

examples/infinite-scroll/README.md

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+# Hydrogen example: infinite scroll collection page
+
+This folder contains an example implementation of [infinite scroll](https://shopify.dev/docs/custom-storefronts/hydrogen/data-fetching/pagination#automatically-load-pages-on-scroll) within a product collection page using the [Pagination component](https://shopify.dev/docs/api/hydrogen/2024-01/components/pagination).
+
+The example uses [`react-intersection-observer`](https://www.npmjs.com/package/react-intersection-observer) to detect when the `Load more` button is in view. A `useEffect` then triggers a navigation to the next page url, which seemlessly loads more products as the user scrolls.
+
+A few side effects of this implementation are:
+
+1. The page progressively enhances, so that when JavaScript has yet to load, the page is still interactive because the user can still click the `Load more` button.
+2. As the user scrolls, the URL automatically changes as new pages are loaded.
+3. Because the implementation uses the `Pagination` component, navigating back to the collection list after clicking on a product automatically maintains the user's scroll position.
+
+## Key files
+
+This folder contains the minimal set of files needed to showcase the implementation.
+Files that aren’t included by default with Hydrogen and that you’ll need to
+create are labeled with 🆕.
+
+| File                                                                       | Description                 |
+| -------------------------------------------------------------------------- | --------------------------- |
+| [`app/routes/collections.$handle.tsx`](app/routes/collections.$handle.tsx) | The product collection page |
+
+## Instructions
+
+### 1. Link your store to inject the required environment variables
+
+```bash
+h2 link
+```
+
+### 2. Edit the route loader
+
+In `app/routes/collections.$handle.tsx`, update the `pageBy` parameter passed to tghe `getPaginationVariables` function call to customize how many products to load at a time.
+
+```ts
+const paginationVariables = getPaginationVariables(request, {
+  pageBy: 8,
+});
+```

examples/infinite-scroll/app/routes/collections.$handle.tsx

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+import {json, redirect, type LoaderFunctionArgs} from '@shopify/remix-oxygen';
+import {
+  useLoaderData,
+  useNavigate,
+  Link,
+  type MetaFunction,
+} from '@remix-run/react';
+import {
+  Pagination,
+  getPaginationVariables,
+  Image,
+  Money,
+} from '@shopify/hydrogen';
+import type {ProductItemFragment} from 'storefrontapi.generated';
+import {useEffect} from 'react';
+import {useVariantUrl} from '~/lib/variants';
+import {useInView} from 'react-intersection-observer';
+
+export const meta: MetaFunction<typeof loader> = ({data}) => {
+  return [{title: `Hydrogen | ${data?.collection.title ?? ''} Collection`}];
+};
+
+export async function loader({request, params, context}: LoaderFunctionArgs) {
+  const {handle} = params;
+  const {storefront} = context;
+  const paginationVariables = getPaginationVariables(request, {
+    pageBy: 8,
+  });
+
+  if (!handle) {
+    return redirect('/collections');
+  }
+
+  const {collection} = await storefront.query(COLLECTION_QUERY, {
+    variables: {handle, ...paginationVariables},
+  });
+
+  if (!collection) {
+    throw new Response(`Collection ${handle} not found`, {
+      status: 404,
+    });
+  }
+  return json({collection});
+}
+
+export default function Collection() {
+  const {collection} = useLoaderData<typeof loader>();
+  const {ref, inView, entry} = useInView();
+
+  return (
+    <div className="collection">
+      <h1>{collection.title}</h1>
+      <p className="collection-description">{collection.description}</p>
+      <Pagination connection={collection.products}>
+        {({
+          nodes,
+          isLoading,
+          PreviousLink,
+          NextLink,
+          state,
+          nextPageUrl,
+          hasNextPage,
+        }) => (
+          <>
+            <PreviousLink>
+              {isLoading ? 'Loading...' : <span>↑ Load previous</span>}
+            </PreviousLink>
+            <ProductsGrid
+              products={nodes}
+              inView={inView}
+              hasNextPage={hasNextPage}
+              nextPageUrl={nextPageUrl}
+              state={state}
+            />
+            <br />
+            <NextLink ref={ref}>
+              <span ref={ref}>
+                {isLoading ? 'Loading...' : <span>Load more yeah ↓</span>}
+              </span>
+            </NextLink>
+          </>
+        )}
+      </Pagination>
+    </div>
+  );
+}
+
+function ProductsGrid({
+  products,
+  inView,
+  hasNextPage,
+  nextPageUrl,
+  state,
+}: {
+  products: ProductItemFragment[];
+  inView: boolean;
+  hasNextPage: boolean;
+  nextPageUrl: string;
+  state: any;
+}) {
+  const navigate = useNavigate();
+
+  useEffect(() => {
+    if (inView && hasNextPage) {
+      navigate(nextPageUrl, {
+        replace: true,
+        preventScrollReset: true,
+        state,
+      });
+    }
+  }, [inView, navigate, state, nextPageUrl, hasNextPage]);
+
+  return (
+    <div className="products-grid">
+      {products.map((product, index) => {
+        return (
+          <ProductItem
+            key={product.id}
+            product={product}
+            loading={index < 8 ? 'eager' : undefined}
+          />
+        );
+      })}
+    </div>
+  );
+}
+
+function ProductItem({
+  product,
+  loading,
+}: {
+  product: ProductItemFragment;
+  loading?: 'eager' | 'lazy';
+}) {
+  const variant = product.variants.nodes[0];
+  const variantUrl = useVariantUrl(product.handle, variant.selectedOptions);
+  return (
+    <Link
+      className="product-item"
+      key={product.id}
+      prefetch="intent"
+      to={variantUrl}
+    >
+      {product.featuredImage && (
+        <Image
+          alt={product.featuredImage.altText || product.title}
+          aspectRatio="1/1"
+          data={product.featuredImage}
+          loading={loading}
+          sizes="(min-width: 45em) 400px, 100vw"
+        />
+      )}
+      <h4>{product.title}</h4>
+      <small>
+        <Money data={product.priceRange.minVariantPrice} />
+      </small>
+    </Link>
+  );
+}
+
+const PRODUCT_ITEM_FRAGMENT = `#graphql
+  fragment MoneyProductItem on MoneyV2 {
+    amount
+    currencyCode
+  }
+  fragment ProductItem on Product {
+    id
+    handle
+    title
+    featuredImage {
+      id
+      altText
+      url
+      width
+      height
+    }
+    priceRange {
+      minVariantPrice {
+        ...MoneyProductItem
+      }
+      maxVariantPrice {
+        ...MoneyProductItem
+      }
+    }
+    variants(first: 1) {
+      nodes {
+        selectedOptions {
+          name
+          value
+        }
+      }
+    }
+  }
+` as const;
+
+// NOTE: https://shopify.dev/docs/api/storefront/2022-04/objects/collection
+const COLLECTION_QUERY = `#graphql
+  ${PRODUCT_ITEM_FRAGMENT}
+  query Collection(
+    $handle: String!
+    $country: CountryCode
+    $language: LanguageCode
+    $first: Int
+    $last: Int
+    $startCursor: String
+    $endCursor: String
+  ) @inContext(country: $country, language: $language) {
+    collection(handle: $handle) {
+      id
+      handle
+      title
+      description
+      products(
+        first: $first,
+        last: $last,
+        before: $startCursor,
+        after: $endCursor
+      ) {
+        nodes {
+          ...ProductItem
+        }
+        pageInfo {
+          hasPreviousPage
+          hasNextPage
+          endCursor
+          startCursor
+        }
+      }
+    }
+  }
+` as const;

examples/infinite-scroll/package.json

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+{
+  "name": "example-infinite-scroll",
+  "private": true,
+  "prettier": "@shopify/prettier-config",
+  "scripts": {
+    "build": "shopify hydrogen build --diff",
+    "dev": "shopify hydrogen dev --codegen --diff",
+    "preview": "npm run build && shopify hydrogen preview",
+    "lint": "eslint --no-error-on-unmatched-pattern --ext .js,.ts,.jsx,.tsx .",
+    "codegen": "shopify hydrogen codegen"
+  },
+  "dependencies": {
+    "react-intersection-observer": "^8.32.1"
+  }
+}

examples/infinite-scroll/tsconfig.json

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+{
+  "extends": "../../templates/skeleton/tsconfig.json",
+  "include": ["./**/*.d.ts", "./**/*.ts", "./**/*.tsx"],
+  "compilerOptions": {
+    "baseUrl": ".",
+    "paths": {
+      "*": ["./*", "../../templates/skeleton/*"],
+      "~/*": ["app/*", "../../templates/skeleton/app/*"]
+    }
+  }
+}