Add infinite scroll to post list

app/javascript/components/Board/PostList.tsx

@@ -1,5 +1,7 @@
 import * as React from 'react';
 
+import InfiniteScroll from 'react-infinite-scroller';
+
 import PostListItem from './PostListItem';
 import Spinner from '../shared/Spinner';
 
@@ -9,14 +11,24 @@ interface Props {
   posts: Array<IPost>;
   areLoading: boolean;
   error: string;
+
+  handleLoadMore(): void;
+  page: number;
+  hasMore: boolean;
 }
 
-const PostList = ({ posts, areLoading, error }: Props) => (
+const PostList = ({ posts, areLoading, error, handleLoadMore, page, hasMore }: Props) => (
   <div className="box postList">
-    { areLoading ? <Spinner /> : null }
     { error ? <span className="error">{error}</span> : null }
-    {
-      posts.map((post, i) => (
+    <InfiniteScroll
+      initialLoad={false}
+      loadMore={handleLoadMore}
+      threshold={50}
+      hasMore={hasMore}
+      loader={<Spinner />}
+      useWindow={true}
+    >
+      {posts.map((post, i) => (
         <PostListItem
           title={post.title}
           description={post.description}
@@ -24,8 +36,8 @@ const PostList = ({ posts, areLoading, error }: Props) => (
 
           key={i}
         />
-      ))
-    }
+      ))}
+    </InfiniteScroll>
   </div>
 );