@shopify/react-html
![npm version](https://badge.fury.io/js/%40shopify%2Freact-html.svg)
A collection of utilities for constructing an HTML document.
Installation
$ yarn add @shopify/react-html
Usage
This package exposes two entrypoints:
@shopify/react-html
: which contains code that can be used on server and client. Code in your app
and client
directories should import from this entrypoint.@shopify/react-html/server
: which contains all of react-html
, but also includes some features that are not safe to run in a browser context. Code in your server
directory should import from this entrypoint.
Note: because this package creates an HTML document, this package is only for applications that are server rendered in Node. Rails apps generally have Rails perform the render of the HTML document, so they do not benefit from any part of this library.
In your server middleware
Your server needs construct an HTML document. To do this, you can use the Html
component and render
function from @shopify/react-html/server
:
import * as React from 'react';
import {render, Html} from '@shopify/react-html/server';
import App from '../app';
export default function middleware(ctx) {
ctx.body = render(
<Html>
<App />
</Html>,
);
}
If you want to make use of the serialization techniques documented below, you must also construct an HtmlManager
instance, pass it to a <HtmlContext.Provider />
component, and call @shopify/react-effect
’s extract
method:
import {extract} from '@shopify/react-effect/server';
import {
render,
Html,
HtmlManager,
HtmlContext,
} from '@shopify/react-html/server';
export default function middleware(ctx) {
const manager = new HtmlManager();
const app = <App />;
await extract(app, {
decorate: element => (
<HtmlContext.Provider value={manager}>{element}</HtmlContext.Provider>
),
});
ctx.body = render(<Html manager={manager}>{app}</Html>);
}
You can also use the Script
, Style
, and Serialize
components detailed in the API reference to manually construct a variety of tags, which you will typically insert into the document with the Html
component’s headMarkup
and bodyMarkup
props.
In your application
In order for link
, meta
, and title
tags to be updated as components are mounted and unmounted, you must render the HeadUpdater
component somewhere in your tree:
function App() {
return (
<>
<HeadUpdater />
<RestOfApp />
</>
);
}
In your client entrypoint
Your client needs to rehydrate the React application. In development, it also needs to remove some of the temporary markup we create to prevent flashes of unstyled content. To do so, use the showPage
function exported from @shopify/react-html
:
import {hydrate} from 'react-dom';
import {showPage} from '@shopify/react-html';
import App from '../app';
hydrate(<App />, document.querySelector('#app'));
showPage();
You do not need to create a Manager
/ Provider
component on the client.
In your application code
Some parts of your application code may have some form of state that must be rehydrated when the server-rendered page is loaded on the client. To do so, application code can use the useSerialized
hook exported from @shopify/react-html
.
useSerialized()
accepts a single string argument for the identifier to use; this will help you find the serialized script
tag if you need to debug later on. It also accepts a generic type argument for the type of the data that will be serialized/ available after deserialization.
The hook returns an array where the first entry is the serialized data (or undefined
, if it was not found), and the second entry is a component that accepts a data
prop that is a function that returns the data to serialize (or a promise for that data).
Note: providing a promise for the data
prop has a catch if you are using @shopify/react-effect
to extract the serializations in server rendering: it expects that you will only provide a promise for the serialization if it can’t be returned synchronously. If you always return a promise, @shopify/react-effect
will assume it always needs to do another render of the tree, which will lead to an infinite loop.
Here is a complete example, using @shopify/react-i18n
’s support for async translations as the data that needs to be serialized:
import {useSerialized} from '@shopify/react-html';
import {I18nContext, Manager} from '@shopify/react-i18n';
interface Props {
locale: string;
children: React.ReactNode;
}
interface Data {
locale: string;
translations: ReturnType<Manager['extract']>;
}
export default function I18n({locale, children}: Props) {
const [serialized, Serialize] = useSerialized<Data>('i18n');
const {locale, translations} = serialized || {locale: explicitLocale};
const manager = new Manager({locale, fallbackLocale: 'en'}, translations);
return (
<>
<I18nContext.Provider value={manager}>{children}</I18nContext.Provider>
<Serialize
data={() => {
const getData = () => ({
locale: manager.details.locale,
translations: manager.extract(),
});
return manager.loading ? manager.resolve().then(getData) : getData();
}}
/>
</>
);
}
The rationale for this approach to handling serialization is available in our original proposal.
API reference
useSerialized()
See the example above for a full exploration of useSerialized
’s API.
createSerializer()
createSerializer
is a legacy API that has been deprecated by useSerialized()
. For full documentation of this API, please refer to older versions of this document. createSerializer
will be removed in the next major version of @shopify/react-html
.
<Html />
The <Html>
component serves as a top level wrapper for a React application, allowing you to avoid needing any kind of server-side template. It is only available from the server entrypoint of this package (@shopify/react-html/server
). The Html
component accepts the following props:
manager
: a Manager
instance. When provided, the Html
component will extract all the information from this object and place it in an appropriate place in the document.children
: the application. It will be rendered to a string and placed inside a div
with an ID of app
.locale
: the language to use for the HTML lang
attribute.styles
: descriptors for any style tags you want to include in the HEAD of the document.scripts
: descriptors for any script tags you want to include in your document. All scripts passed to this property will be deferred by appending them to the end of the document. We encourage this as a default because it improves the initial rendering performance of your page.blockingScripts
: descriptors for any script tags you want to include in the HEAD of the document. These will block HTML parsing until they are evaluated, so use them carefully.headMarkup
: additional JSX to be embedded in the head of the document (after styles, but before blocking scripts).bodyMarkup
: additional JSX to be embedded in the body of the document (before serialization markup and deferred scripts).
import {Html} from '@shopify/react-html/server';
const html = (
<Html
locale="fr"
styles={[{path: '/style.css'}]}
scripts={[{path: '/script.js'}]}
>
<App />
</Html>
);
<Style />
The <Style />
component lets you render <link>
tags in your document dynamically as part of your react app. It supports all of the props of a basic link
tag, but forces some properties to be the values needed for a stylesheet. In general, prefer the styles
prop of the Html
component instead of using this component explicitly.
import {Style} from '@shopify/react-html';
<Style
href="./some-style.css"
integrity="some-integrity-hash"
crossOrigin="anonymous"
/>;
<Script />
The <Script />
component lets you render <script>
tags in your document dynamically as part of your react app. It supports all the props of a basic script
tag. In general, prefer the scripts
prop of the Html
component instead of using this component explicitly.
import {Script} from '@shopify/react-html';
<Script
src="./some-script.js"
integrity="some-integrity-hash"
crossOrigin="anonymous"
/>;
<HeadUpdater />
The <HeadUpdater />
component is responsible for updating the head in response to link
, meta
, and title
changes. You should only render one of these in your entire app.
useLink()
and <Link />
Renders a <link />
tag in the head with the specified attributes. On the server, links are recorded in the Manager
and automatically applied to the Html
component. On the client, the <link />
tags are updated in a deferred callback to minimize DOM manipulations.
Both the hook and component versions accept any properties you would supply to a <link />
tag. If you are using this component to create a favicon, use the useFavicon()
/ <Favicon />
component instead.
useMeta()
and <Meta />
Renders a <meta />
tag in the head with the specified attributes. This component uses the same approach to render these tags as detailed for the <Link />
component above.
Both the hook and component versions accept any properties you would supply to a <meta />
tag.
useTitle()
and <Title />
Renders a <title />
tag in the head with the specified attributes. If multiple <Title />
components/ useTitle()
hooks are rendered in your app, the last one (usually, the most deeply nested) will be applied.
This component accepts a string child (and the hook accepts a single string argument), which will be used to set the title of the page.
useFavicon()
and <Favicon />
Renders a <link />
tag with the necessary props to specify a favicon. Accepts a source
prop that should be the image source for the favicon (the hook accepts a single string argument for the source).
usePreconnect()
and <Preconnect />
Renders a <link />
tag that preconnects the browser to the host specified by the source
prop. You can read more about preconnecting on Google’s guide to resource prioritization.
<Responsive />
Renders a <Meta />
tag that specifies additional functionality and dimensions to mobile devices. Accepts a coverNotch
property which allows the viewport to fill the device display, and an allowPinchToZoom
property to the allow the app to be zoomed-in. Both properties default to true
.
<AppleHomeScreen />
Renders iOS-specific <Meta />
tags and <Link />
tags to specify additional visual information on how to display the app on iOS devices. Accepts an icons
property as an array of image attributes to be used for the app‘s home screen icon. Also accepts a startUpImage
url to render while the app is loading after being launched from the home screen.
<Serialize />
The Serialize component takes care of rendering a script
tag with a serialized version of the data
prop. It is provided for incremental adoption of the useSerialized()
method of generating serializations documented above.
render()
The render()
function creates a stringified version of the HTML document with an appropriate DOCTYPE. It is only available from the server entrypoint of this package (@shopify/react-html/server
).
import {render, Html} from '@shopify/react-html/sever';
const markup = render(<Html>Hello world!</Html>);
showPage()
This function encapsulates the logic for showing the page in development, where it is hidden on the initial render by default. You must call this function from your client entry point, usually right after hydrating your React app. It returns a promise that resolves after the document is guaranteed to be visible.
getSerialized<Data>()
To help in migration, this function can imperatively return the parsed value of a serialization. It returns the data cast to whatever is passed for Data
. It should only be called on the client.
Migration