File: deferred-data.md | Updated: 11/15/2025
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React Example: Deferred Data
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Code ExplorerCode
Interactive SandboxSandbox
.vscode
src
main.tsx
styles.css
.gitignore
README.md
index.html
package.json
postcss.config.mjs
tsconfig.json
vite.config.js
tsx
import React from 'react'
import ReactDOM from 'react-dom/client'
import {
Await,
ErrorComponent,
Link,
MatchRoute,
Outlet,
RouterProvider,
createRootRoute,
createRoute,
createRouter,
defer,
} from '@tanstack/react-router'
import { TanStackRouterDevtools } from '@tanstack/react-router-devtools'
import axios from 'redaxios'
import type { ErrorComponentProps } from '@tanstack/react-router'
import './styles.css'
type PostType = {
id: string
title: string
body: string
}
type CommentType = {
id: string
postId: string
name: string
email: string
body: string
}
const fetchPosts = async () => {
console.info('Fetching posts...')
await new Promise((r) => setTimeout(r, 100))
return axios
.get<Array<PostType>>('https://jsonplaceholder.typicode.com/posts')
.then((r) => r.data.slice(0, 10))
}
const fetchPost = async (postId: string) => {
console.info(`Fetching post with id ${postId}...`)
const commentsPromise = new Promise((r) => setTimeout(r, 2000))
.then(() =>
axios.get<Array<CommentType>>(
`https://jsonplaceholder.typicode.com/comments?postId=${postId}`,
),
)
.then((r) => r.data)
const post = await new Promise((r) => setTimeout(r, 1000))
.then(() =>
axios.get<PostType>(
`https://jsonplaceholder.typicode.com/posts/${postId}`,
),
)
.catch((err) => {
if (err.status === 404) {
throw new NotFoundError(`Post with id "${postId}" not found!`)
}
throw err
})
.then((r) => r.data)
return {
post,
commentsPromise: defer(commentsPromise),
}
}
function Spinner({ show, wait }: { show?: boolean; wait?: `delay-${number}` }) {
return (
<div
className={`inline-block animate-spin px-3 transition ${
(show ?? true)
? `opacity-1 duration-500 ${wait ?? 'delay-300'}`
: 'duration-500 opacity-0 delay-0'
}`}
>
⍥
</div>
)
}
const rootRoute = createRootRoute({
component: RootComponent,
})
function RootComponent() {
return (
<>
<div className="p-2 flex gap-2 text-lg">
<Link
to="/"
activeProps={{
className: 'font-bold',
}}
activeOptions={{ exact: true }}
>
Home
</Link>{' '}
<Link
to="/posts"
activeProps={{
className: 'font-bold',
}}
>
Posts
</Link>
</div>
<hr />
<Outlet />
{/* Start rendering router matches */}
<TanStackRouterDevtools position="bottom-right" />
</>
)
}
const indexRoute = createRoute({
getParentRoute: () => rootRoute,
path: '/',
}).update({
component: IndexComponent,
})
function IndexComponent() {
return (
<div className="p-2">
<h3>Welcome Home!</h3>
</div>
)
}
const postsRoute = createRoute({
getParentRoute: () => rootRoute,
path: 'posts',
loader: fetchPosts,
component: PostsComponent,
})
function PostsComponent() {
const posts = postsRoute.useLoaderData()
return (
<div className="p-2 flex gap-2">
<ul className="list-disc pl-4">
{[...posts, { id: 'i-do-not-exist', title: 'Non-existent Post' }].map(
(post) => {
return (
<li key={post.id} className="whitespace-nowrap">
<Link
to={postRoute.to}
params={{
postId: post.id,
}}
className="flex py-1 text-blue-600 hover:opacity-75 gap-2 items-center"
activeProps={{ className: 'font-bold underline' }}
>
<div>{post.title.substring(0, 20)}</div>
<MatchRoute
to={postRoute.to}
params={{
postId: post.id,
}}
pending
>
{(match) => {
return <Spinner show={!!match} wait="delay-0" />
}}
</MatchRoute>
</Link>
</li>
)
},
)}
</ul>
<hr />
<Outlet />
</div>
)
}
class NotFoundError extends Error {}
const postRoute = createRoute({
getParentRoute: () => postsRoute,
path: '$postId',
loader: async ({ params: { postId } }) => fetchPost(postId),
errorComponent: PostErrorComponent,
component: PostComponent,
})
function PostErrorComponent({ error }: ErrorComponentProps) {
if (error instanceof NotFoundError) {
return <div>{error.message}</div>
}
return <ErrorComponent error={error} />
}
function PostComponent() {
const { post, commentsPromise } = postRoute.useLoaderData()
return (
<div className="space-y-2">
<h4 className="text-xl font-bold underline">{post.title}</h4>
<div className="text-sm">{post.body}</div>
<React.Suspense
fallback={
<div className="flex items-center gap-2">
<Spinner />
Loading comments...
</div>
}
key={post.id}
>
<Await promise={commentsPromise}>
{(comments) => {
return (
<div className="space-y-2">
<h5 className="text-lg font-bold underline">Comments</h5>
{comments.map((comment) => {
return (
<div key={comment.id}>
<h6 className="text-md font-bold">{comment.name}</h6>
<div className="text-sm italic opacity-50">
{comment.email}
</div>
<div className="text-sm">{comment.body}</div>
</div>
)
})}
</div>
)
}}
</Await>
</React.Suspense>
</div>
)
}
const routeTree = rootRoute.addChildren([\
postsRoute.addChildren([postRoute]),\
indexRoute,\
])
// Set up a Router instance
const router = createRouter({
routeTree,
defaultPreload: 'intent',
scrollRestoration: true,
})
// Register things for typesafety
declare module '@tanstack/react-router' {
interface Register {
router: typeof router
}
}
const rootElement = document.getElementById('app')!
if (!rootElement.innerHTML) {
const root = ReactDOM.createRoot(rootElement)
root.render(<RouterProvider router={router} />)
}
import React from 'react'
import ReactDOM from 'react-dom/client'
import {
Await,
ErrorComponent,
Link,
MatchRoute,
Outlet,
RouterProvider,
createRootRoute,
createRoute,
createRouter,
defer,
} from '@tanstack/react-router'
import { TanStackRouterDevtools } from '@tanstack/react-router-devtools'
import axios from 'redaxios'
import type { ErrorComponentProps } from '@tanstack/react-router'
import './styles.css'
type PostType = {
id: string
title: string
body: string
}
type CommentType = {
id: string
postId: string
name: string
email: string
body: string
}
const fetchPosts = async () => {
console.info('Fetching posts...')
await new Promise((r) => setTimeout(r, 100))
return axios
.get<Array<PostType>>('https://jsonplaceholder.typicode.com/posts')
.then((r) => r.data.slice(0, 10))
}
const fetchPost = async (postId: string) => {
console.info(`Fetching post with id ${postId}...`)
const commentsPromise = new Promise((r) => setTimeout(r, 2000))
.then(() =>
axios.get<Array<CommentType>>(
`https://jsonplaceholder.typicode.com/comments?postId=${postId}`,
),
)
.then((r) => r.data)
const post = await new Promise((r) => setTimeout(r, 1000))
.then(() =>
axios.get<PostType>(
`https://jsonplaceholder.typicode.com/posts/${postId}`,
),
)
.catch((err) => {
if (err.status === 404) {
throw new NotFoundError(`Post with id "${postId}" not found!`)
}
throw err
})
.then((r) => r.data)
return {
post,
commentsPromise: defer(commentsPromise),
}
}
function Spinner({ show, wait }: { show?: boolean; wait?: `delay-${number}` }) {
return (
<div
className={`inline-block animate-spin px-3 transition ${
(show ?? true)
? `opacity-1 duration-500 ${wait ?? 'delay-300'}`
: 'duration-500 opacity-0 delay-0'
}`}
>
⍥
</div>
)
}
const rootRoute = createRootRoute({
component: RootComponent,
})
function RootComponent() {
return (
<>
<div className="p-2 flex gap-2 text-lg">
<Link
to="/"
activeProps={{
className: 'font-bold',
}}
activeOptions={{ exact: true }}
>
Home
</Link>{' '}
<Link
to="/posts"
activeProps={{
className: 'font-bold',
}}
>
Posts
</Link>
</div>
<hr />
<Outlet />
{/* Start rendering router matches */}
<TanStackRouterDevtools position="bottom-right" />
</>
)
}
const indexRoute = createRoute({
getParentRoute: () => rootRoute,
path: '/',
}).update({
component: IndexComponent,
})
function IndexComponent() {
return (
<div className="p-2">
<h3>Welcome Home!</h3>
</div>
)
}
const postsRoute = createRoute({
getParentRoute: () => rootRoute,
path: 'posts',
loader: fetchPosts,
component: PostsComponent,
})
function PostsComponent() {
const posts = postsRoute.useLoaderData()
return (
<div className="p-2 flex gap-2">
<ul className="list-disc pl-4">
{[...posts, { id: 'i-do-not-exist', title: 'Non-existent Post' }].map(
(post) => {
return (
<li key={post.id} className="whitespace-nowrap">
<Link
to={postRoute.to}
params={{
postId: post.id,
}}
className="flex py-1 text-blue-600 hover:opacity-75 gap-2 items-center"
activeProps={{ className: 'font-bold underline' }}
>
<div>{post.title.substring(0, 20)}</div>
<MatchRoute
to={postRoute.to}
params={{
postId: post.id,
}}
pending
>
{(match) => {
return <Spinner show={!!match} wait="delay-0" />
}}
</MatchRoute>
</Link>
</li>
)
},
)}
</ul>
<hr />
<Outlet />
</div>
)
}
class NotFoundError extends Error {}
const postRoute = createRoute({
getParentRoute: () => postsRoute,
path: '$postId',
loader: async ({ params: { postId } }) => fetchPost(postId),
errorComponent: PostErrorComponent,
component: PostComponent,
})
function PostErrorComponent({ error }: ErrorComponentProps) {
if (error instanceof NotFoundError) {
return <div>{error.message}</div>
}
return <ErrorComponent error={error} />
}
function PostComponent() {
const { post, commentsPromise } = postRoute.useLoaderData()
return (
<div className="space-y-2">
<h4 className="text-xl font-bold underline">{post.title}</h4>
<div className="text-sm">{post.body}</div>
<React.Suspense
fallback={
<div className="flex items-center gap-2">
<Spinner />
Loading comments...
</div>
}
key={post.id}
>
<Await promise={commentsPromise}>
{(comments) => {
return (
<div className="space-y-2">
<h5 className="text-lg font-bold underline">Comments</h5>
{comments.map((comment) => {
return (
<div key={comment.id}>
<h6 className="text-md font-bold">{comment.name}</h6>
<div className="text-sm italic opacity-50">
{comment.email}
</div>
<div className="text-sm">{comment.body}</div>
</div>
)
})}
</div>
)
}}
</Await>
</React.Suspense>
</div>
)
}
const routeTree = rootRoute.addChildren([\
postsRoute.addChildren([postRoute]),\
indexRoute,\
])
// Set up a Router instance
const router = createRouter({
routeTree,
defaultPreload: 'intent',
scrollRestoration: true,
})
// Register things for typesafety
declare module '@tanstack/react-router' {
interface Register {
router: typeof router
}
}
const rootElement = document.getElementById('app')!
if (!rootElement.innerHTML) {
const root = ReactDOM.createRoot(rootElement)
root.render(<RouterProvider router={router} />)
}
