[18] Use hydrateRoot and root.unmount. (#4473)

Author: rickhanlonii

content/docs/reference-dom-elements.md

@@ -117,7 +117,7 @@ Normally, there is a warning when an element with children is also marked as `co
 
 If you use server-side React rendering, normally there is a warning when the server and the client render different content. However, in some rare cases, it is very hard or impossible to guarantee an exact match. For example, timestamps are expected to differ on the server and on the client.
 
-If you set `suppressHydrationWarning` to `true`, React will not warn you about mismatches in the attributes and the content of that element. It only works one level deep, and is intended to be used as an escape hatch. Don't overuse it. You can read more about hydration in the [`ReactDOM.hydrate()` documentation](/docs/react-dom.html#hydrate).
+If you set `suppressHydrationWarning` to `true`, React will not warn you about mismatches in the attributes and the content of that element. It only works one level deep, and is intended to be used as an escape hatch. Don't overuse it. You can read more about hydration in the [`ReactDOM.hydrateRoot()` documentation](/docs/react-dom-client.html#hydrateroot).
 
 ### value {#value}
 

content/docs/reference-react-dom-server.md

@@ -39,7 +39,7 @@ ReactDOMServer.renderToString(element)
 
 Render a React element to its initial HTML. React will return an HTML string. You can use this method to generate HTML on the server and send the markup down on the initial request for faster page loads and to allow search engines to crawl your pages for SEO purposes.
 
-If you call [`ReactDOM.hydrate()`](/docs/react-dom.html#hydrate) on a node that already has this server-rendered markup, React will preserve it and only attach event handlers, allowing you to have a very performant first-load experience.
+If you call [`ReactDOM.hydrateRoot()`](/docs/react-dom-client.html#hydrateroot) on a node that already has this server-rendered markup, React will preserve it and only attach event handlers, allowing you to have a very performant first-load experience.
 
 * * *
 
@@ -51,7 +51,7 @@ ReactDOMServer.renderToStaticMarkup(element)
 
 Similar to [`renderToString`](#rendertostring), except this doesn't create extra DOM attributes that React uses internally, such as `data-reactroot`. This is useful if you want to use React as a simple static page generator, as stripping away the extra attributes can save some bytes.
 
-If you plan to use React on the client to make the markup interactive, do not use this method. Instead, use [`renderToString`](#rendertostring) on the server and [`ReactDOM.hydrate()`](/docs/react-dom.html#hydrate) on the client.
+If you plan to use React on the client to make the markup interactive, do not use this method. Instead, use [`renderToString`](#rendertostring) on the server and [`ReactDOM.hydrateRoot()`](/docs/react-dom-client.html#hydrateroot) on the client.
 
 * * *
 
@@ -63,7 +63,7 @@ ReactDOMServer.renderToNodeStream(element)
 
 Render a React element to its initial HTML. Returns a [Readable stream](https://nodejs.org/api/stream.html#stream_readable_streams) that outputs an HTML string. The HTML output by this stream is exactly equal to what [`ReactDOMServer.renderToString`](#rendertostring) would return. You can use this method to generate HTML on the server and send the markup down on the initial request for faster page loads and to allow search engines to crawl your pages for SEO purposes.
 
-If you call [`ReactDOM.hydrate()`](/docs/react-dom.html#hydrate) on a node that already has this server-rendered markup, React will preserve it and only attach event handlers, allowing you to have a very performant first-load experience.
+If you call [`ReactDOM.hydrateRoot()`](/docs/react-dom-client.html#hydrateroot) on a node that already has this server-rendered markup, React will preserve it and only attach event handlers, allowing you to have a very performant first-load experience.
 
 > Note:
 >
@@ -83,7 +83,7 @@ Similar to [`renderToNodeStream`](#rendertonodestream), except this doesn't crea
 
 The HTML output by this stream is exactly equal to what [`ReactDOMServer.renderToStaticMarkup`](#rendertostaticmarkup) would return.
 
-If you plan to use React on the client to make the markup interactive, do not use this method. Instead, use [`renderToNodeStream`](#rendertonodestream) on the server and [`ReactDOM.hydrate()`](/docs/react-dom.html#hydrate) on the client.
+If you plan to use React on the client to make the markup interactive, do not use this method. Instead, use [`renderToNodeStream`](#rendertonodestream) on the server and [`ReactDOM.hydrateRoot()`](/docs/react-dom-client.html#hydrateroot) on the client.
 
 > Note:
 >

content/docs/reference-react-dom.md

@@ -113,6 +113,10 @@ Remember to be mindful of user experience on slow connections. The JavaScript co
 unmountComponentAtNode(container)
 ```
 
+> Note:
+>
+> `unmountComponentAtNode` has been replaced with `root.unmount()` in React 18. See [createRoot](/docs/react-dom-client.html#createroot) for more info.
+
 Remove a mounted React component from the DOM and clean up its event handlers and state. If no component was mounted in the container, calling this function does nothing. Returns `true` if a component was unmounted and `false` if there was no component to unmount.
 
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