-
+
-
-
-
-
-
-
-
-
-
- React
-
+
+
+
+
+
+
+
+
+
+
+ React
+
+
+
+ }
+ >
+
+
+
+
+
+
+
+ );
+}
+
+function VideoInfo({ id }) {
+ const details = use(fetchVideoDetails(id));
+ return (
+
+
{details.title}
+
{details.description}
+
+ );
+}
+```
+
+```js src/Home.js hidden
+import { Video } from "./Videos";
+import Layout from "./Layout";
+import { fetchVideos } from "./data";
+import { useId, useState, use } from "react";
+import { IconSearch } from "./Icons";
+
+function SearchInput({ value, onChange }) {
+ const id = useId();
+ return (
+
+ );
+}
+
+function filterVideos(videos, query) {
+ const keywords = query
+ .toLowerCase()
+ .split(" ")
+ .filter((s) => s !== "");
+ if (keywords.length === 0) {
+ return videos;
+ }
+ return videos.filter((video) => {
+ const words = (video.title + " " + video.description)
+ .toLowerCase()
+ .split(" ");
+ return keywords.every((kw) => words.some((w) => w.includes(kw)));
+ });
+}
+
+export default function Home() {
+ const videos = use(fetchVideos());
+ const count = videos.length;
+ const [searchText, setSearchText] = useState("");
+ const foundVideos = filterVideos(videos, searchText);
+ return (
+
{count} Videos}>
+
+
+ {foundVideos.length === 0 && (
+
No results
+ )}
+
+ {foundVideos.map((video) => (
+
+ ))}
+
+
+
+ );
+}
+
+```
+
+```js src/Icons.js hidden
+export function ChevronLeft() {
+ return (
+
+ );
+}
+
+export function PauseIcon() {
+ return (
+
+ );
+}
+
+export function PlayIcon() {
+ return (
+
+ );
+}
+export function Heart({liked, animate}) {
+ return (
+ <>
+
+
+
+
+ );
+}
+
+export function IconSearch(props) {
+ return (
+
+ );
+}
+```
+
+```js src/Layout.js hidden
+import {unstable_ViewTransition as ViewTransition} from 'react';
+import { useIsNavPending } from "./router";
+
+export default function Page({ heading, children }) {
+ const isPending = useIsNavPending();
+ return (
+
+
+
+ {/* Custom classes based on transition type. */}
+
+ {heading}
+
+ {isPending && }
+
+
+ {/* Opt-out of ViewTransition for the content. */}
+ {/* Content can define it's own ViewTransition. */}
+
+
+
+
+ );
+}
+```
+
+```js src/LikeButton.js hidden
+import {useState} from 'react';
+import {Heart} from './Icons';
+
+// A hack since we don't actually have a backend.
+// Unlike local state, this survives videos being filtered.
+const likedVideos = new Set();
+
+export default function LikeButton({video}) {
+ const [isLiked, setIsLiked] = useState(() => likedVideos.has(video.id));
+ const [animate, setAnimate] = useState(false);
+ return (
+
+ );
+}
+```
+
+```js src/Videos.js hidden
+import { useState, unstable_ViewTransition as ViewTransition } from "react";
+import LikeButton from "./LikeButton";
+import { useRouter } from "./router";
+import { PauseIcon, PlayIcon } from "./Icons";
+import { startTransition } from "react";
+
+export function Thumbnail({ video, children }) {
+ // Add a name to animate with a shared element transition.
+ // This uses the default animation, no additional css needed.
+ return (
+
+
+ {children}
+
+
+ );
+}
+
+export function VideoControls() {
+ const [isPlaying, setIsPlaying] = useState(false);
+
+ return (
+
+ startTransition(() => {
+ setIsPlaying((p) => !p);
+ })
+ }
+ >
+ {isPlaying ? : }
+
+ );
+}
+
+export function Video({ video }) {
+ const { navigate } = useRouter();
+
+ return (
+
+
{
+ e.preventDefault();
+ navigate(`/video/${video.id}`);
+ }}
+ >
+
+
+
+
{video.title}
+
{video.description}
+
+
+
+
+ );
+}
+```
+
+
+```js src/data.js hidden
+const videos = [
+ {
+ id: '1',
+ title: 'First video',
+ description: 'Video description',
+ image: 'blue',
+ },
+ {
+ id: '2',
+ title: 'Second video',
+ description: 'Video description',
+ image: 'red',
+ },
+ {
+ id: '3',
+ title: 'Third video',
+ description: 'Video description',
+ image: 'green',
+ },
+ {
+ id: '4',
+ title: 'Fourth video',
+ description: 'Video description',
+ image: 'purple',
+ },
+ {
+ id: '5',
+ title: 'Fifth video',
+ description: 'Video description',
+ image: 'yellow',
+ },
+ {
+ id: '6',
+ title: 'Sixth video',
+ description: 'Video description',
+ image: 'gray',
+ },
+];
+
+let videosCache = new Map();
+let videoCache = new Map();
+let videoDetailsCache = new Map();
+const VIDEO_DELAY = 1;
+const VIDEO_DETAILS_DELAY = 1000;
+export function fetchVideos() {
+ if (videosCache.has(0)) {
+ return videosCache.get(0);
+ }
+ const promise = new Promise((resolve) => {
+ setTimeout(() => {
+ resolve(videos);
+ }, VIDEO_DELAY);
+ });
+ videosCache.set(0, promise);
+ return promise;
+}
+
+export function fetchVideo(id) {
+ if (videoCache.has(id)) {
+ return videoCache.get(id);
+ }
+ const promise = new Promise((resolve) => {
+ setTimeout(() => {
+ resolve(videos.find((video) => video.id === id));
+ }, VIDEO_DELAY);
+ });
+ videoCache.set(id, promise);
+ return promise;
+}
+
+export function fetchVideoDetails(id) {
+ if (videoDetailsCache.has(id)) {
+ return videoDetailsCache.get(id);
+ }
+ const promise = new Promise((resolve) => {
+ setTimeout(() => {
+ resolve(videos.find((video) => video.id === id));
+ }, VIDEO_DETAILS_DELAY);
+ });
+ videoDetailsCache.set(id, promise);
+ return promise;
+}
+```
+
+```js src/router.js hidden
+import {useState, createContext, use, useTransition, useLayoutEffect, useEffect, unstable_addTransitionType as addTransitionType} from "react";
+
+export function Router({ children }) {
+ const [isPending, startTransition] = useTransition();
+ const [routerState, setRouterState] = useState({pendingNav: () => {}, url: document.location.pathname});
+ function navigate(url) {
+ startTransition(() => {
+ // Transition type for the cause "nav forward"
+ addTransitionType('nav-forward');
+ go(url);
+ });
+ }
+ function navigateBack(url) {
+ startTransition(() => {
+ // Transition type for the cause "nav backward"
+ addTransitionType('nav-back');
+ go(url);
+ });
+ }
+
+ function go(url) {
+ setRouterState({
+ url,
+ pendingNav() {
+ window.history.pushState({}, "", url);
+ },
+ });
+ }
+
+ useEffect(() => {
+ function handlePopState() {
+ // This should not animate because restoration has to be synchronous.
+ // Even though it's a transition.
+ startTransition(() => {
+ setRouterState({
+ url: document.location.pathname + document.location.search,
+ pendingNav() {
+ // Noop. URL has already updated.
+ },
+ });
+ });
+ }
+ window.addEventListener("popstate", handlePopState);
+ return () => {
+ window.removeEventListener("popstate", handlePopState);
+ };
+ }, []);
+ const pendingNav = routerState.pendingNav;
+ useLayoutEffect(() => {
+ pendingNav();
+ }, [pendingNav]);
+
+ return (
+
+ {children}
+
+ );
+}
+
+const RouterContext = createContext({ url: "/", params: {} });
+
+export function useRouter() {
+ return use(RouterContext);
+}
+
+export function useIsNavPending() {
+ return use(RouterContext).isPending;
+}
+
+```
+
+```css src/styles.css hidden
+@font-face {
+ font-family: Optimistic Text;
+ src: url(https://react.dev/fonts/Optimistic_Text_W_Rg.woff2) format("woff2");
+ font-weight: 400;
+ font-style: normal;
+ font-display: swap;
+}
+
+@font-face {
+ font-family: Optimistic Text;
+ src: url(https://react.dev/fonts/Optimistic_Text_W_Md.woff2) format("woff2");
+ font-weight: 500;
+ font-style: normal;
+ font-display: swap;
+}
+
+@font-face {
+ font-family: Optimistic Text;
+ src: url(https://react.dev/fonts/Optimistic_Text_W_Bd.woff2) format("woff2");
+ font-weight: 600;
+ font-style: normal;
+ font-display: swap;
+}
+
+@font-face {
+ font-family: Optimistic Text;
+ src: url(https://react.dev/fonts/Optimistic_Text_W_Bd.woff2) format("woff2");
+ font-weight: 700;
+ font-style: normal;
+ font-display: swap;
+}
+
+* {
+ box-sizing: border-box;
+}
+
+html {
+ background-image: url(https://react.dev/images/meta-gradient-dark.png);
+ background-size: 100%;
+ background-position: -100%;
+ background-color: rgb(64 71 86);
+ background-repeat: no-repeat;
+ height: 100%;
+ width: 100%;
+}
+
+body {
+ font-family: Optimistic Text, -apple-system, ui-sans-serif, system-ui, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol, Noto Color Emoji;
+ padding: 10px 0 10px 0;
+ margin: 0;
+ display: flex;
+ justify-content: center;
+}
+
+#root {
+ flex: 1 1;
+ height: auto;
+ background-color: #fff;
+ border-radius: 10px;
+ max-width: 450px;
+ min-height: 600px;
+ padding-bottom: 10px;
+}
+
+h1 {
+ margin-top: 0;
+ font-size: 22px;
+}
+
+h2 {
+ margin-top: 0;
+ font-size: 20px;
+}
+
+h3 {
+ margin-top: 0;
+ font-size: 18px;
+}
+
+h4 {
+ margin-top: 0;
+ font-size: 16px;
+}
+
+h5 {
+ margin-top: 0;
+ font-size: 14px;
+}
+
+h6 {
+ margin-top: 0;
+ font-size: 12px;
+}
+
+code {
+ font-size: 1.2em;
+}
+
+ul {
+ padding-inline-start: 20px;
+}
+
+.sr-only {
+ position: absolute;
+ width: 1px;
+ height: 1px;
+ padding: 0;
+ margin: -1px;
+ overflow: hidden;
+ clip: rect(0, 0, 0, 0);
+ white-space: nowrap;
+ border-width: 0;
+}
+
+.absolute {
+ position: absolute;
+}
+
+.overflow-visible {
+ overflow: visible;
+}
+
+.visible {
+ overflow: visible;
+}
+
+.fit {
+ width: fit-content;
+}
+
+
+/* Layout */
+.page {
+ display: flex;
+ flex-direction: column;
+ height: 100%;
+}
+
+.top-hero {
+ height: 200px;
+ display: flex;
+ justify-content: center;
+ align-items: center;
+ background-image: conic-gradient(
+ from 90deg at -10% 100%,
+ #2b303b 0deg,
+ #2b303b 90deg,
+ #16181d 1turn
+ );
+}
+
+.bottom {
+ flex: 1;
+ overflow: auto;
+}
+
+.top-nav {
+ display: flex;
+ align-items: center;
+ justify-content: space-between;
+ margin-bottom: 0;
+ padding: 0 12px;
+ top: 0;
+ width: 100%;
+ height: 44px;
+ color: #23272f;
+ font-weight: 700;
+ font-size: 20px;
+ z-index: 100;
+ cursor: default;
+}
+
+.content {
+ padding: 0 12px;
+ margin-top: 4px;
+}
+
+
+.loader {
+ color: #23272f;
+ font-size: 3px;
+ width: 1em;
+ margin-right: 18px;
+ height: 1em;
+ border-radius: 50%;
+ position: relative;
+ text-indent: -9999em;
+ animation: loading-spinner 1.3s infinite linear;
+ animation-delay: 200ms;
+ transform: translateZ(0);
+}
+
+@keyframes loading-spinner {
+ 0%,
+ 100% {
+ box-shadow: 0 -3em 0 0.2em,
+ 2em -2em 0 0em, 3em 0 0 -1em,
+ 2em 2em 0 -1em, 0 3em 0 -1em,
+ -2em 2em 0 -1em, -3em 0 0 -1em,
+ -2em -2em 0 0;
+ }
+ 12.5% {
+ box-shadow: 0 -3em 0 0, 2em -2em 0 0.2em,
+ 3em 0 0 0, 2em 2em 0 -1em, 0 3em 0 -1em,
+ -2em 2em 0 -1em, -3em 0 0 -1em,
+ -2em -2em 0 -1em;
+ }
+ 25% {
+ box-shadow: 0 -3em 0 -0.5em,
+ 2em -2em 0 0, 3em 0 0 0.2em,
+ 2em 2em 0 0, 0 3em 0 -1em,
+ -2em 2em 0 -1em, -3em 0 0 -1em,
+ -2em -2em 0 -1em;
+ }
+ 37.5% {
+ box-shadow: 0 -3em 0 -1em, 2em -2em 0 -1em,
+ 3em 0em 0 0, 2em 2em 0 0.2em, 0 3em 0 0em,
+ -2em 2em 0 -1em, -3em 0em 0 -1em, -2em -2em 0 -1em;
+ }
+ 50% {
+ box-shadow: 0 -3em 0 -1em, 2em -2em 0 -1em,
+ 3em 0 0 -1em, 2em 2em 0 0em, 0 3em 0 0.2em,
+ -2em 2em 0 0, -3em 0em 0 -1em, -2em -2em 0 -1em;
+ }
+ 62.5% {
+ box-shadow: 0 -3em 0 -1em, 2em -2em 0 -1em,
+ 3em 0 0 -1em, 2em 2em 0 -1em, 0 3em 0 0,
+ -2em 2em 0 0.2em, -3em 0 0 0, -2em -2em 0 -1em;
+ }
+ 75% {
+ box-shadow: 0em -3em 0 -1em, 2em -2em 0 -1em,
+ 3em 0em 0 -1em, 2em 2em 0 -1em, 0 3em 0 -1em,
+ -2em 2em 0 0, -3em 0em 0 0.2em, -2em -2em 0 0;
+ }
+ 87.5% {
+ box-shadow: 0em -3em 0 0, 2em -2em 0 -1em,
+ 3em 0 0 -1em, 2em 2em 0 -1em, 0 3em 0 -1em,
+ -2em 2em 0 0, -3em 0em 0 0, -2em -2em 0 0.2em;
+ }
+}
+
+/* LikeButton */
+.like-button {
+ outline-offset: 2px;
+ position: relative;
+ display: flex;
+ align-items: center;
+ justify-content: center;
+ width: 2.5rem;
+ height: 2.5rem;
+ cursor: pointer;
+ border-radius: 9999px;
+ border: none;
+ outline: none 2px;
+ color: #5e687e;
+ background: none;
+}
+
+.like-button:focus {
+ color: #a6423a;
+ background-color: rgba(166, 66, 58, .05);
+}
+
+.like-button:active {
+ color: #a6423a;
+ background-color: rgba(166, 66, 58, .05);
+ transform: scaleX(0.95) scaleY(0.95);
+}
+
+.like-button:hover {
+ background-color: #f6f7f9;
+}
+
+.like-button.liked {
+ color: #a6423a;
+}
+
+/* Icons */
+@keyframes circle {
+ 0% {
+ transform: scale(0);
+ stroke-width: 16px;
+ }
+
+ 50% {
+ transform: scale(.5);
+ stroke-width: 16px;
+ }
+
+ to {
+ transform: scale(1);
+ stroke-width: 0;
+ }
+}
+
+.circle {
+ color: rgba(166, 66, 58, .5);
+ transform-origin: center;
+ transition-property: all;
+ transition-duration: .15s;
+ transition-timing-function: cubic-bezier(.4,0,.2,1);
+}
+
+.circle.liked.animate {
+ animation: circle .3s forwards;
+}
+
+.heart {
+ width: 1.5rem;
+ height: 1.5rem;
+}
+
+.heart.liked {
+ transform-origin: center;
+ transition-property: all;
+ transition-duration: .15s;
+ transition-timing-function: cubic-bezier(.4, 0, .2, 1);
+}
+
+.heart.liked.animate {
+ animation: scale .35s ease-in-out forwards;
+}
+
+.control-icon {
+ color: hsla(0, 0%, 100%, .5);
+ filter: drop-shadow(0 20px 13px rgba(0, 0, 0, .03)) drop-shadow(0 8px 5px rgba(0, 0, 0, .08));
+}
+
+.chevron-left {
+ margin-top: 2px;
+ rotate: 90deg;
+}
+
+
+/* Video */
+.thumbnail {
+ position: relative;
+ aspect-ratio: 16 / 9;
+ display: flex;
+ overflow: hidden;
+ flex-direction: column;
+ justify-content: center;
+ align-items: center;
+ border-radius: 0.5rem;
+ outline-offset: 2px;
+ width: 8rem;
+ vertical-align: middle;
+ background-color: #ffffff;
+ background-size: cover;
+ user-select: none;
+}
+
+.thumbnail.blue {
+ background-image: conic-gradient(at top right, #c76a15, #087ea4, #2b3491);
+}
+
+.thumbnail.red {
+ background-image: conic-gradient(at top right, #c76a15, #a6423a, #2b3491);
+}
+
+.thumbnail.green {
+ background-image: conic-gradient(at top right, #c76a15, #388f7f, #2b3491);
+}
+
+.thumbnail.purple {
+ background-image: conic-gradient(at top right, #c76a15, #575fb7, #2b3491);
+}
+
+.thumbnail.yellow {
+ background-image: conic-gradient(at top right, #c76a15, #FABD62, #2b3491);
+}
+
+.thumbnail.gray {
+ background-image: conic-gradient(at top right, #c76a15, #4E5769, #2b3491);
+}
+
+.video {
+ display: flex;
+ flex-direction: row;
+ gap: 0.75rem;
+ align-items: center;
+}
+
+.video .link {
+ display: flex;
+ flex-direction: row;
+ flex: 1 1 0;
+ gap: 0.125rem;
+ outline-offset: 4px;
+ cursor: pointer;
+}
+
+.video .info {
+ display: flex;
+ flex-direction: column;
+ justify-content: center;
+ margin-left: 8px;
+ gap: 0.125rem;
+}
+
+.video .info:hover {
+ text-decoration: underline;
+}
+
+.video-title {
+ font-size: 15px;
+ line-height: 1.25;
+ font-weight: 700;
+ color: #23272f;
+}
+
+.video-description {
+ color: #5e687e;
+ font-size: 13px;
+}
+
+/* Details */
+.details .thumbnail {
+ position: relative;
+ aspect-ratio: 16 / 9;
+ display: flex;
+ overflow: hidden;
+ flex-direction: column;
+ justify-content: center;
+ align-items: center;
+ border-radius: 0.5rem;
+ outline-offset: 2px;
+ width: 100%;
+ vertical-align: middle;
+ background-color: #ffffff;
+ background-size: cover;
+ user-select: none;
+}
+
+.video-details-title {
+ margin-top: 8px;
+}
+
+.video-details-speaker {
+ display: flex;
+ gap: 8px;
+ margin-top: 10px
+}
+
+.back {
+ display: flex;
+ align-items: center;
+ margin-left: -5px;
+ cursor: pointer;
+}
+
+.back:hover {
+ text-decoration: underline;
+}
+
+.info-title {
+ font-size: 1.5rem;
+ font-weight: 700;
+ line-height: 1.25;
+ margin: 8px 0 0 0 ;
+}
+
+.info-description {
+ margin: 8px 0 0 0;
+}
+
+.controls {
+ cursor: pointer;
+}
+
+.fallback {
+ background: #f6f7f8 linear-gradient(to right, #e6e6e6 5%, #cccccc 25%, #e6e6e6 35%) no-repeat;
+ background-size: 800px 104px;
+ display: block;
+ line-height: 1.25;
+ margin: 8px 0 0 0;
+ border-radius: 5px;
+ overflow: hidden;
+
+ animation: 1s linear 1s infinite shimmer;
+ animation-delay: 300ms;
+ animation-duration: 1s;
+ animation-fill-mode: forwards;
+ animation-iteration-count: infinite;
+ animation-name: shimmer;
+ animation-timing-function: linear;
+}
+
+
+.fallback.title {
+ width: 130px;
+ height: 30px;
+
+}
+
+.fallback.description {
+ width: 150px;
+ height: 21px;
+}
+
+@keyframes shimmer {
+ 0% {
+ background-position: -468px 0;
+ }
+
+ 100% {
+ background-position: 468px 0;
+ }
+}
+
+.search {
+ margin-bottom: 10px;
+}
+.search-input {
+ width: 100%;
+ position: relative;
+}
+
+.search-icon {
+ position: absolute;
+ top: 0;
+ bottom: 0;
+ inset-inline-start: 0;
+ display: flex;
+ align-items: center;
+ padding-inline-start: 1rem;
+ pointer-events: none;
+ color: #99a1b3;
+}
+
+.search-input input {
+ display: flex;
+ padding-inline-start: 2.75rem;
+ padding-top: 10px;
+ padding-bottom: 10px;
+ width: 100%;
+ text-align: start;
+ background-color: rgb(235 236 240);
+ outline: 2px solid transparent;
+ cursor: pointer;
+ border: none;
+ align-items: center;
+ color: rgb(35 39 47);
+ border-radius: 9999px;
+ vertical-align: middle;
+ font-size: 15px;
+}
+
+.search-input input:hover, .search-input input:active {
+ background-color: rgb(235 236 240/ 0.8);
+ color: rgb(35 39 47/ 0.8);
+}
+
+/* Home */
+.video-list {
+ position: relative;
+}
+
+.video-list .videos {
+ display: flex;
+ flex-direction: column;
+ gap: 1rem;
+ overflow-y: auto;
+ height: 100%;
+}
+```
+
+
+```css src/animations.css
+/* Slide the fallback down */
+::view-transition-old(.slide-down) {
+ animation: 150ms ease-out both fade-out, 150ms ease-out both slide-down;
+}
+
+/* Slide the content up */
+::view-transition-new(.slide-up) {
+ animation: 210ms ease-in 150ms both fade-in, 400ms ease-in both slide-up;
+}
+
+/* Define the new keyframes */
+@keyframes slide-up {
+ from {
+ transform: translateY(10px);
+ }
+ to {
+ transform: translateY(0);
+ }
+}
+
+@keyframes slide-down {
+ from {
+ transform: translateY(0);
+ }
+ to {
+ transform: translateY(10px);
+ }
+}
+
+/* Previously defined animations below */
+
+/* Animations for view transition classed added by transition type */
+::view-transition-old(.slide-forward) {
+ /* when sliding forward, the "old" page should slide out to left. */
+ animation: 150ms cubic-bezier(0.4, 0, 1, 1) both fade-out,
+ 400ms cubic-bezier(0.4, 0, 0.2, 1) both slide-to-left;
+}
+
+::view-transition-new(.slide-forward) {
+ /* when sliding forward, the "new" page should slide in from right. */
+ animation: 210ms cubic-bezier(0, 0, 0.2, 1) 150ms both fade-in,
+ 400ms cubic-bezier(0.4, 0, 0.2, 1) both slide-from-right;
+}
+
+::view-transition-old(.slide-back) {
+ /* when sliding back, the "old" page should slide out to right. */
+ animation: 150ms cubic-bezier(0.4, 0, 1, 1) both fade-out,
+ 400ms cubic-bezier(0.4, 0, 0.2, 1) both slide-to-right;
+}
+
+::view-transition-new(.slide-back) {
+ /* when sliding back, the "new" page should slide in from left. */
+ animation: 210ms cubic-bezier(0, 0, 0.2, 1) 150ms both fade-in,
+ 400ms cubic-bezier(0.4, 0, 0.2, 1) both slide-from-left;
+}
+
+/* Keyframes to support our animations above. */
+@keyframes fade-in {
+ from {
+ opacity: 0;
+ }
+}
+
+@keyframes fade-out {
+ to {
+ opacity: 0;
+ }
+}
+
+@keyframes slide-to-right {
+ to {
+ transform: translateX(50px);
+ }
+}
+
+@keyframes slide-from-right {
+ from {
+ transform: translateX(50px);
+ }
+ to {
+ transform: translateX(0);
+ }
+}
+
+@keyframes slide-to-left {
+ to {
+ transform: translateX(-50px);
+ }
+}
+
+@keyframes slide-from-left {
+ from {
+ transform: translateX(-50px);
+ }
+ to {
+ transform: translateX(0);
+ }
+}
+
+/* Default .slow-fade. */
+::view-transition-old(.slow-fade) {
+ animation-duration: 500ms;
+}
+
+::view-transition-new(.slow-fade) {
+ animation-duration: 500ms;
+}
+```
+
+```js src/index.js hidden
+import React, {StrictMode} from 'react';
+import {createRoot} from 'react-dom/client';
+import './styles.css';
+import './animations.css';
+
+import App from './App';
+import {Router} from './router';
+
+const root = createRoot(document.getElementById('root'));
+root.render(
+
+
+
+
+
+);
+```
+
+```json package.json hidden
+{
+ "dependencies": {
+ "react": "experimental",
+ "react-dom": "experimental",
+ "react-scripts": "latest"
+ },
+ "scripts": {
+ "start": "react-scripts start",
+ "build": "react-scripts build",
+ "test": "react-scripts test --env=jsdom",
+ "eject": "react-scripts eject"
+ }
+}
+```
+
+
+
+We can also provide custom animations using an `exit` on the fallback, and `enter` on the content:
+
+```js {3,8}
+
+
+
+ }
+>
+
+
+
+
+```
+
+Here's how we'll define `slide-down` and `slide-up` with CSS:
+
+```css {1, 6}
+::view-transition-old(.slide-down) {
+ /* Slide the fallback down */
+ animation: ...;
+}
+
+::view-transition-new(.slide-up) {
+ /* Slide the content up */
+ animation: ...;
+}
+```
+
+Now, the Suspense content replaces the fallback with a sliding animation:
+
+
+
+```js src/App.js hidden
+import { unstable_ViewTransition as ViewTransition } from "react";
+import Details from "./Details";
+import Home from "./Home";
+import { useRouter } from "./router";
+
+export default function App() {
+ const { url } = useRouter();
+
+ // Default slow-fade animation.
+ return (
+
+ {url === "/" ? :
+ }
+ >
+
+
+
+
+
+
+
+ );
+}
+
+function VideoInfo({ id }) {
+ const details = use(fetchVideoDetails(id));
+ return (
+ <>
+
{details.title}
+
{details.description}
+
+ );
+}
+```
+
+```js src/Home.js hidden
+import { Video } from "./Videos";
+import Layout from "./Layout";
+import { fetchVideos } from "./data";
+import { useId, useState, use } from "react";
+import { IconSearch } from "./Icons";
+
+function SearchInput({ value, onChange }) {
+ const id = useId();
+ return (
+
+ );
+}
+
+function filterVideos(videos, query) {
+ const keywords = query
+ .toLowerCase()
+ .split(" ")
+ .filter((s) => s !== "");
+ if (keywords.length === 0) {
+ return videos;
+ }
+ return videos.filter((video) => {
+ const words = (video.title + " " + video.description)
+ .toLowerCase()
+ .split(" ");
+ return keywords.every((kw) => words.some((w) => w.includes(kw)));
+ });
+}
+
+export default function Home() {
+ const videos = use(fetchVideos());
+ const count = videos.length;
+ const [searchText, setSearchText] = useState("");
+ const foundVideos = filterVideos(videos, searchText);
+ return (
+
{count} Videos}>
+
+
+ {foundVideos.length === 0 && (
+
No results
+ )}
+
+ {foundVideos.map((video) => (
+
+ ))}
+
+
+
+ );
+}
+
+```
+
+```js src/Icons.js hidden
+export function ChevronLeft() {
+ return (
+
+ );
+}
+
+export function PauseIcon() {
+ return (
+
+ );
+}
+
+export function PlayIcon() {
+ return (
+
+ );
+}
+export function Heart({liked, animate}) {
+ return (
+ <>
+
+
+
+
+ );
+}
+
+export function IconSearch(props) {
+ return (
+
+ );
+}
+```
+
+```js src/Layout.js hidden
+import {unstable_ViewTransition as ViewTransition} from 'react';
+import { useIsNavPending } from "./router";
+
+export default function Page({ heading, children }) {
+ const isPending = useIsNavPending();
+ return (
+
+
+
+ {/* Custom classes based on transition type. */}
+
+ {heading}
+
+ {isPending && }
+
+
+ {/* Opt-out of ViewTransition for the content. */}
+ {/* Content can define it's own ViewTransition. */}
+
+
+
+
+ );
+}
+```
+
+```js src/LikeButton.js hidden
+import {useState} from 'react';
+import {Heart} from './Icons';
+
+// A hack since we don't actually have a backend.
+// Unlike local state, this survives videos being filtered.
+const likedVideos = new Set();
+
+export default function LikeButton({video}) {
+ const [isLiked, setIsLiked] = useState(() => likedVideos.has(video.id));
+ const [animate, setAnimate] = useState(false);
+ return (
+
+ );
+}
+```
+
+```js src/Videos.js hidden
+import { useState, unstable_ViewTransition as ViewTransition } from "react";
+import LikeButton from "./LikeButton";
+import { useRouter } from "./router";
+import { PauseIcon, PlayIcon } from "./Icons";
+import { startTransition } from "react";
+
+export function Thumbnail({ video, children }) {
+ // Add a name to animate with a shared element transition.
+ // This uses the default animation, no additional css needed.
+ return (
+
+
+ {children}
+
+
+ );
+}
+
+export function VideoControls() {
+ const [isPlaying, setIsPlaying] = useState(false);
+
+ return (
+
+ startTransition(() => {
+ setIsPlaying((p) => !p);
+ })
+ }
+ >
+ {isPlaying ? : }
+
+ );
+}
+
+export function Video({ video }) {
+ const { navigate } = useRouter();
+
+ return (
+
+
{
+ e.preventDefault();
+ navigate(`/video/${video.id}`);
+ }}
+ >
+
+
+
+
{video.title}
+
{video.description}
+
+
+
+
+ );
+}
+```
+
+
+```js src/data.js hidden
+const videos = [
+ {
+ id: '1',
+ title: 'First video',
+ description: 'Video description',
+ image: 'blue',
+ },
+ {
+ id: '2',
+ title: 'Second video',
+ description: 'Video description',
+ image: 'red',
+ },
+ {
+ id: '3',
+ title: 'Third video',
+ description: 'Video description',
+ image: 'green',
+ },
+ {
+ id: '4',
+ title: 'Fourth video',
+ description: 'Video description',
+ image: 'purple',
+ },
+ {
+ id: '5',
+ title: 'Fifth video',
+ description: 'Video description',
+ image: 'yellow',
+ },
+ {
+ id: '6',
+ title: 'Sixth video',
+ description: 'Video description',
+ image: 'gray',
+ },
+];
+
+let videosCache = new Map();
+let videoCache = new Map();
+let videoDetailsCache = new Map();
+const VIDEO_DELAY = 1;
+const VIDEO_DETAILS_DELAY = 1000;
+export function fetchVideos() {
+ if (videosCache.has(0)) {
+ return videosCache.get(0);
+ }
+ const promise = new Promise((resolve) => {
+ setTimeout(() => {
+ resolve(videos);
+ }, VIDEO_DELAY);
+ });
+ videosCache.set(0, promise);
+ return promise;
+}
+
+export function fetchVideo(id) {
+ if (videoCache.has(id)) {
+ return videoCache.get(id);
+ }
+ const promise = new Promise((resolve) => {
+ setTimeout(() => {
+ resolve(videos.find((video) => video.id === id));
+ }, VIDEO_DELAY);
+ });
+ videoCache.set(id, promise);
+ return promise;
+}
+
+export function fetchVideoDetails(id) {
+ if (videoDetailsCache.has(id)) {
+ return videoDetailsCache.get(id);
+ }
+ const promise = new Promise((resolve) => {
+ setTimeout(() => {
+ resolve(videos.find((video) => video.id === id));
+ }, VIDEO_DETAILS_DELAY);
+ });
+ videoDetailsCache.set(id, promise);
+ return promise;
+}
+```
+
+```js src/router.js hidden
+import {useState, createContext, use, useTransition, useLayoutEffect, useEffect, unstable_addTransitionType as addTransitionType} from "react";
+
+export function Router({ children }) {
+ const [isPending, startTransition] = useTransition();
+ const [routerState, setRouterState] = useState({pendingNav: () => {}, url: document.location.pathname});
+ function navigate(url) {
+ startTransition(() => {
+ // Transition type for the cause "nav forward"
+ addTransitionType('nav-forward');
+ go(url);
+ });
+ }
+ function navigateBack(url) {
+ startTransition(() => {
+ // Transition type for the cause "nav backward"
+ addTransitionType('nav-back');
+ go(url);
+ });
+ }
+
+ function go(url) {
+ setRouterState({
+ url,
+ pendingNav() {
+ window.history.pushState({}, "", url);
+ },
+ });
+ }
+
+ useEffect(() => {
+ function handlePopState() {
+ // This should not animate because restoration has to be synchronous.
+ // Even though it's a transition.
+ startTransition(() => {
+ setRouterState({
+ url: document.location.pathname + document.location.search,
+ pendingNav() {
+ // Noop. URL has already updated.
+ },
+ });
+ });
+ }
+ window.addEventListener("popstate", handlePopState);
+ return () => {
+ window.removeEventListener("popstate", handlePopState);
+ };
+ }, []);
+ const pendingNav = routerState.pendingNav;
+ useLayoutEffect(() => {
+ pendingNav();
+ }, [pendingNav]);
+
+ return (
+
+ {children}
+
+ );
+}
+
+const RouterContext = createContext({ url: "/", params: {} });
+
+export function useRouter() {
+ return use(RouterContext);
+}
+
+export function useIsNavPending() {
+ return use(RouterContext).isPending;
+}
+
+```
+
+```css src/styles.css hidden
+@font-face {
+ font-family: Optimistic Text;
+ src: url(https://react.dev/fonts/Optimistic_Text_W_Rg.woff2) format("woff2");
+ font-weight: 400;
+ font-style: normal;
+ font-display: swap;
+}
+
+@font-face {
+ font-family: Optimistic Text;
+ src: url(https://react.dev/fonts/Optimistic_Text_W_Md.woff2) format("woff2");
+ font-weight: 500;
+ font-style: normal;
+ font-display: swap;
+}
+
+@font-face {
+ font-family: Optimistic Text;
+ src: url(https://react.dev/fonts/Optimistic_Text_W_Bd.woff2) format("woff2");
+ font-weight: 600;
+ font-style: normal;
+ font-display: swap;
+}
+
+@font-face {
+ font-family: Optimistic Text;
+ src: url(https://react.dev/fonts/Optimistic_Text_W_Bd.woff2) format("woff2");
+ font-weight: 700;
+ font-style: normal;
+ font-display: swap;
+}
+
+* {
+ box-sizing: border-box;
+}
+
+html {
+ background-image: url(https://react.dev/images/meta-gradient-dark.png);
+ background-size: 100%;
+ background-position: -100%;
+ background-color: rgb(64 71 86);
+ background-repeat: no-repeat;
+ height: 100%;
+ width: 100%;
+}
+
+body {
+ font-family: Optimistic Text, -apple-system, ui-sans-serif, system-ui, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol, Noto Color Emoji;
+ padding: 10px 0 10px 0;
+ margin: 0;
+ display: flex;
+ justify-content: center;
+}
+
+#root {
+ flex: 1 1;
+ height: auto;
+ background-color: #fff;
+ border-radius: 10px;
+ max-width: 450px;
+ min-height: 600px;
+ padding-bottom: 10px;
+}
+
+h1 {
+ margin-top: 0;
+ font-size: 22px;
+}
+
+h2 {
+ margin-top: 0;
+ font-size: 20px;
+}
+
+h3 {
+ margin-top: 0;
+ font-size: 18px;
+}
+
+h4 {
+ margin-top: 0;
+ font-size: 16px;
+}
+
+h5 {
+ margin-top: 0;
+ font-size: 14px;
+}
+
+h6 {
+ margin-top: 0;
+ font-size: 12px;
+}
+
+code {
+ font-size: 1.2em;
+}
+
+ul {
+ padding-inline-start: 20px;
+}
+
+.sr-only {
+ position: absolute;
+ width: 1px;
+ height: 1px;
+ padding: 0;
+ margin: -1px;
+ overflow: hidden;
+ clip: rect(0, 0, 0, 0);
+ white-space: nowrap;
+ border-width: 0;
+}
+
+.absolute {
+ position: absolute;
+}
+
+.overflow-visible {
+ overflow: visible;
+}
+
+.visible {
+ overflow: visible;
+}
+
+.fit {
+ width: fit-content;
+}
+
+
+/* Layout */
+.page {
+ display: flex;
+ flex-direction: column;
+ height: 100%;
+}
+
+.top-hero {
+ height: 200px;
+ display: flex;
+ justify-content: center;
+ align-items: center;
+ background-image: conic-gradient(
+ from 90deg at -10% 100%,
+ #2b303b 0deg,
+ #2b303b 90deg,
+ #16181d 1turn
+ );
+}
+
+.bottom {
+ flex: 1;
+ overflow: auto;
+}
+
+.top-nav {
+ display: flex;
+ align-items: center;
+ justify-content: space-between;
+ margin-bottom: 0;
+ padding: 0 12px;
+ top: 0;
+ width: 100%;
+ height: 44px;
+ color: #23272f;
+ font-weight: 700;
+ font-size: 20px;
+ z-index: 100;
+ cursor: default;
+}
+
+.content {
+ padding: 0 12px;
+ margin-top: 4px;
+}
+
+
+.loader {
+ color: #23272f;
+ font-size: 3px;
+ width: 1em;
+ margin-right: 18px;
+ height: 1em;
+ border-radius: 50%;
+ position: relative;
+ text-indent: -9999em;
+ animation: loading-spinner 1.3s infinite linear;
+ animation-delay: 200ms;
+ transform: translateZ(0);
+}
+
+@keyframes loading-spinner {
+ 0%,
+ 100% {
+ box-shadow: 0 -3em 0 0.2em,
+ 2em -2em 0 0em, 3em 0 0 -1em,
+ 2em 2em 0 -1em, 0 3em 0 -1em,
+ -2em 2em 0 -1em, -3em 0 0 -1em,
+ -2em -2em 0 0;
+ }
+ 12.5% {
+ box-shadow: 0 -3em 0 0, 2em -2em 0 0.2em,
+ 3em 0 0 0, 2em 2em 0 -1em, 0 3em 0 -1em,
+ -2em 2em 0 -1em, -3em 0 0 -1em,
+ -2em -2em 0 -1em;
+ }
+ 25% {
+ box-shadow: 0 -3em 0 -0.5em,
+ 2em -2em 0 0, 3em 0 0 0.2em,
+ 2em 2em 0 0, 0 3em 0 -1em,
+ -2em 2em 0 -1em, -3em 0 0 -1em,
+ -2em -2em 0 -1em;
+ }
+ 37.5% {
+ box-shadow: 0 -3em 0 -1em, 2em -2em 0 -1em,
+ 3em 0em 0 0, 2em 2em 0 0.2em, 0 3em 0 0em,
+ -2em 2em 0 -1em, -3em 0em 0 -1em, -2em -2em 0 -1em;
+ }
+ 50% {
+ box-shadow: 0 -3em 0 -1em, 2em -2em 0 -1em,
+ 3em 0 0 -1em, 2em 2em 0 0em, 0 3em 0 0.2em,
+ -2em 2em 0 0, -3em 0em 0 -1em, -2em -2em 0 -1em;
+ }
+ 62.5% {
+ box-shadow: 0 -3em 0 -1em, 2em -2em 0 -1em,
+ 3em 0 0 -1em, 2em 2em 0 -1em, 0 3em 0 0,
+ -2em 2em 0 0.2em, -3em 0 0 0, -2em -2em 0 -1em;
+ }
+ 75% {
+ box-shadow: 0em -3em 0 -1em, 2em -2em 0 -1em,
+ 3em 0em 0 -1em, 2em 2em 0 -1em, 0 3em 0 -1em,
+ -2em 2em 0 0, -3em 0em 0 0.2em, -2em -2em 0 0;
+ }
+ 87.5% {
+ box-shadow: 0em -3em 0 0, 2em -2em 0 -1em,
+ 3em 0 0 -1em, 2em 2em 0 -1em, 0 3em 0 -1em,
+ -2em 2em 0 0, -3em 0em 0 0, -2em -2em 0 0.2em;
+ }
+}
+
+/* LikeButton */
+.like-button {
+ outline-offset: 2px;
+ position: relative;
+ display: flex;
+ align-items: center;
+ justify-content: center;
+ width: 2.5rem;
+ height: 2.5rem;
+ cursor: pointer;
+ border-radius: 9999px;
+ border: none;
+ outline: none 2px;
+ color: #5e687e;
+ background: none;
+}
+
+.like-button:focus {
+ color: #a6423a;
+ background-color: rgba(166, 66, 58, .05);
+}
+
+.like-button:active {
+ color: #a6423a;
+ background-color: rgba(166, 66, 58, .05);
+ transform: scaleX(0.95) scaleY(0.95);
+}
+
+.like-button:hover {
+ background-color: #f6f7f9;
+}
+
+.like-button.liked {
+ color: #a6423a;
+}
+
+/* Icons */
+@keyframes circle {
+ 0% {
+ transform: scale(0);
+ stroke-width: 16px;
+ }
+
+ 50% {
+ transform: scale(.5);
+ stroke-width: 16px;
+ }
+
+ to {
+ transform: scale(1);
+ stroke-width: 0;
+ }
+}
+
+.circle {
+ color: rgba(166, 66, 58, .5);
+ transform-origin: center;
+ transition-property: all;
+ transition-duration: .15s;
+ transition-timing-function: cubic-bezier(.4,0,.2,1);
+}
+
+.circle.liked.animate {
+ animation: circle .3s forwards;
+}
+
+.heart {
+ width: 1.5rem;
+ height: 1.5rem;
+}
+
+.heart.liked {
+ transform-origin: center;
+ transition-property: all;
+ transition-duration: .15s;
+ transition-timing-function: cubic-bezier(.4, 0, .2, 1);
+}
+
+.heart.liked.animate {
+ animation: scale .35s ease-in-out forwards;
+}
+
+.control-icon {
+ color: hsla(0, 0%, 100%, .5);
+ filter: drop-shadow(0 20px 13px rgba(0, 0, 0, .03)) drop-shadow(0 8px 5px rgba(0, 0, 0, .08));
+}
+
+.chevron-left {
+ margin-top: 2px;
+ rotate: 90deg;
+}
+
+
+/* Video */
+.thumbnail {
+ position: relative;
+ aspect-ratio: 16 / 9;
+ display: flex;
+ overflow: hidden;
+ flex-direction: column;
+ justify-content: center;
+ align-items: center;
+ border-radius: 0.5rem;
+ outline-offset: 2px;
+ width: 8rem;
+ vertical-align: middle;
+ background-color: #ffffff;
+ background-size: cover;
+ user-select: none;
+}
+
+.thumbnail.blue {
+ background-image: conic-gradient(at top right, #c76a15, #087ea4, #2b3491);
+}
+
+.thumbnail.red {
+ background-image: conic-gradient(at top right, #c76a15, #a6423a, #2b3491);
+}
+
+.thumbnail.green {
+ background-image: conic-gradient(at top right, #c76a15, #388f7f, #2b3491);
+}
+
+.thumbnail.purple {
+ background-image: conic-gradient(at top right, #c76a15, #575fb7, #2b3491);
+}
+
+.thumbnail.yellow {
+ background-image: conic-gradient(at top right, #c76a15, #FABD62, #2b3491);
+}
+
+.thumbnail.gray {
+ background-image: conic-gradient(at top right, #c76a15, #4E5769, #2b3491);
+}
+
+.video {
+ display: flex;
+ flex-direction: row;
+ gap: 0.75rem;
+ align-items: center;
+}
+
+.video .link {
+ display: flex;
+ flex-direction: row;
+ flex: 1 1 0;
+ gap: 0.125rem;
+ outline-offset: 4px;
+ cursor: pointer;
+}
+
+.video .info {
+ display: flex;
+ flex-direction: column;
+ justify-content: center;
+ margin-left: 8px;
+ gap: 0.125rem;
+}
+
+.video .info:hover {
+ text-decoration: underline;
+}
+
+.video-title {
+ font-size: 15px;
+ line-height: 1.25;
+ font-weight: 700;
+ color: #23272f;
+}
+
+.video-description {
+ color: #5e687e;
+ font-size: 13px;
+}
+
+/* Details */
+.details .thumbnail {
+ position: relative;
+ aspect-ratio: 16 / 9;
+ display: flex;
+ overflow: hidden;
+ flex-direction: column;
+ justify-content: center;
+ align-items: center;
+ border-radius: 0.5rem;
+ outline-offset: 2px;
+ width: 100%;
+ vertical-align: middle;
+ background-color: #ffffff;
+ background-size: cover;
+ user-select: none;
+}
+
+.video-details-title {
+ margin-top: 8px;
+}
+
+.video-details-speaker {
+ display: flex;
+ gap: 8px;
+ margin-top: 10px
+}
+
+.back {
+ display: flex;
+ align-items: center;
+ margin-left: -5px;
+ cursor: pointer;
+}
+
+.back:hover {
+ text-decoration: underline;
+}
+
+.info-title {
+ font-size: 1.5rem;
+ font-weight: 700;
+ line-height: 1.25;
+ margin: 8px 0 0 0 ;
+}
+
+.info-description {
+ margin: 8px 0 0 0;
+}
+
+.controls {
+ cursor: pointer;
+}
+
+.fallback {
+ background: #f6f7f8 linear-gradient(to right, #e6e6e6 5%, #cccccc 25%, #e6e6e6 35%) no-repeat;
+ background-size: 800px 104px;
+ display: block;
+ line-height: 1.25;
+ margin: 8px 0 0 0;
+ border-radius: 5px;
+ overflow: hidden;
+
+ animation: 1s linear 1s infinite shimmer;
+ animation-delay: 300ms;
+ animation-duration: 1s;
+ animation-fill-mode: forwards;
+ animation-iteration-count: infinite;
+ animation-name: shimmer;
+ animation-timing-function: linear;
+}
+
+
+.fallback.title {
+ width: 130px;
+ height: 30px;
+
+}
+
+.fallback.description {
+ width: 150px;
+ height: 21px;
+}
+
+@keyframes shimmer {
+ 0% {
+ background-position: -468px 0;
+ }
+
+ 100% {
+ background-position: 468px 0;
+ }
+}
+
+.search {
+ margin-bottom: 10px;
+}
+.search-input {
+ width: 100%;
+ position: relative;
+}
+
+.search-icon {
+ position: absolute;
+ top: 0;
+ bottom: 0;
+ inset-inline-start: 0;
+ display: flex;
+ align-items: center;
+ padding-inline-start: 1rem;
+ pointer-events: none;
+ color: #99a1b3;
+}
+
+.search-input input {
+ display: flex;
+ padding-inline-start: 2.75rem;
+ padding-top: 10px;
+ padding-bottom: 10px;
+ width: 100%;
+ text-align: start;
+ background-color: rgb(235 236 240);
+ outline: 2px solid transparent;
+ cursor: pointer;
+ border: none;
+ align-items: center;
+ color: rgb(35 39 47);
+ border-radius: 9999px;
+ vertical-align: middle;
+ font-size: 15px;
+}
+
+.search-input input:hover, .search-input input:active {
+ background-color: rgb(235 236 240/ 0.8);
+ color: rgb(35 39 47/ 0.8);
+}
+
+/* Home */
+.video-list {
+ position: relative;
+}
+
+.video-list .videos {
+ display: flex;
+ flex-direction: column;
+ gap: 1rem;
+ overflow-y: auto;
+ height: 100%;
+}
+```
+
+
+```css src/animations.css
+/* Slide the fallback down */
+::view-transition-old(.slide-down) {
+ animation: 150ms ease-out both fade-out, 150ms ease-out both slide-down;
+}
+
+/* Slide the content up */
+::view-transition-new(.slide-up) {
+ animation: 210ms ease-in 150ms both fade-in, 400ms ease-in both slide-up;
+}
+
+/* Define the new keyframes */
+@keyframes slide-up {
+ from {
+ transform: translateY(10px);
+ }
+ to {
+ transform: translateY(0);
+ }
+}
+
+@keyframes slide-down {
+ from {
+ transform: translateY(0);
+ }
+ to {
+ transform: translateY(10px);
+ }
+}
+
+/* Previously defined animations below */
+
+/* Animations for view transition classed added by transition type */
+::view-transition-old(.slide-forward) {
+ /* when sliding forward, the "old" page should slide out to left. */
+ animation: 150ms cubic-bezier(0.4, 0, 1, 1) both fade-out,
+ 400ms cubic-bezier(0.4, 0, 0.2, 1) both slide-to-left;
+}
+
+::view-transition-new(.slide-forward) {
+ /* when sliding forward, the "new" page should slide in from right. */
+ animation: 210ms cubic-bezier(0, 0, 0.2, 1) 150ms both fade-in,
+ 400ms cubic-bezier(0.4, 0, 0.2, 1) both slide-from-right;
+}
+
+::view-transition-old(.slide-back) {
+ /* when sliding back, the "old" page should slide out to right. */
+ animation: 150ms cubic-bezier(0.4, 0, 1, 1) both fade-out,
+ 400ms cubic-bezier(0.4, 0, 0.2, 1) both slide-to-right;
+}
+
+::view-transition-new(.slide-back) {
+ /* when sliding back, the "new" page should slide in from left. */
+ animation: 210ms cubic-bezier(0, 0, 0.2, 1) 150ms both fade-in,
+ 400ms cubic-bezier(0.4, 0, 0.2, 1) both slide-from-left;
+}
+
+/* Keyframes to support our animations above. */
+@keyframes fade-in {
+ from {
+ opacity: 0;
+ }
+}
+
+@keyframes fade-out {
+ to {
+ opacity: 0;
+ }
+}
+
+@keyframes slide-to-right {
+ to {
+ transform: translateX(50px);
+ }
+}
+
+@keyframes slide-from-right {
+ from {
+ transform: translateX(50px);
+ }
+ to {
+ transform: translateX(0);
+ }
+}
+
+@keyframes slide-to-left {
+ to {
+ transform: translateX(-50px);
+ }
+}
+
+@keyframes slide-from-left {
+ from {
+ transform: translateX(-50px);
+ }
+ to {
+ transform: translateX(0);
+ }
+}
+
+/* Default .slow-fade. */
+::view-transition-old(.slow-fade) {
+ animation-duration: 500ms;
+}
+
+::view-transition-new(.slow-fade) {
+ animation-duration: 500ms;
+}
+```
+
+```js src/index.js hidden
+import React, {StrictMode} from 'react';
+import {createRoot} from 'react-dom/client';
+import './styles.css';
+import './animations.css';
+
+import App from './App';
+import {Router} from './router';
+
+const root = createRoot(document.getElementById('root'));
+root.render(
+
+
+
+
+
+);
+```
+
+```json package.json hidden
+{
+ "dependencies": {
+ "react": "experimental",
+ "react-dom": "experimental",
+ "react-scripts": "latest"
+ },
+ "scripts": {
+ "start": "react-scripts start",
+ "build": "react-scripts build",
+ "test": "react-scripts test --env=jsdom",
+ "eject": "react-scripts eject"
+ }
+}
+```
+
+
+
+
+### Animating Lists {/*animating-lists*/}
+
+You can also use `
` to animate lists of items as they re-order, like in a searchable list of items:
+
+```js {3,5}
+
+ {filteredVideos.map((video) => (
+
+
+
+ ))}
+
+```
+
+To activate the ViewTransition, we can use `useDeferredValue`:
+
+```js {2}
+const [searchText, setSearchText] = useState('');
+const deferredSearchText = useDeferredValue(searchText);
+const filteredVideos = filterVideos(videos, deferredSearchText);
+```
+
+Now the items animate as you type in the search bar:
+
+
+
+```js src/App.js hidden
+import { unstable_ViewTransition as ViewTransition } from "react";
+import Details from "./Details";
+import Home from "./Home";
+import { useRouter } from "./router";
+
+export default function App() {
+ const { url } = useRouter();
+
+ // Default slow-fade animation.
+ return (
+
+ {url === "/" ? :
+ }
+ >
+ {/* Animate the content up */}
+
+
+
+
+ );
+}
+
+function VideoInfoFallback() {
+ return (
+ <>
+
+
+
+ );
+}
+
+export default function Details() {
+ const { url, navigateBack } = useRouter();
+ const videoId = url.split("/").pop();
+ const video = use(fetchVideo(videoId));
+
+ return (
+
{
+ navigateBack("/");
+ }}
+ >
+ Back
+