JSX

hono/jsx で、 HTML を JSX 構文で書くことができます。

hono/jsx はクライアントでも動作しますが、サーバー側でコンテンツをレンダリングするとき最も頻繁に使うことになるでしょう。ここでは、サーバーとクライアントの両方に共通する、 JSX に関するいくつかのことを説明します。

設定

JSX を使うために tsconfig.json を変更します:

tsconfig.json:

json

{
  "compilerOptions": {
    "jsx": "react-jsx",
    "jsxImportSource": "hono/jsx"
  }
}

あるいは、プラグマを使用します:

/** @jsx jsx */
/** @jsxImportSource hono/jsx */

For Deno, you have to modify the deno.json instead of the tsconfig.json:

json

{
  "compilerOptions": {
    "jsx": "precompile",
    "jsxImportSource": "hono/jsx"
  }
}

使い方

index.tsx:

tsx

import { Hono } from 'hono'
import type { FC } from 'hono/jsx'

const app = new Hono()

const Layout: FC = (props) => {
  return (
    <html>
      <body>{props.children}</body>
    </html>
  )
}

const Top: FC<{ messages: string[] }> = (props: {
  messages: string[]
}) => {
  return (
    <Layout>
      <h1>Hello Hono!</h1>
      <ul>
        {props.messages.map((message) => {
          return <li>{message}!!</li>
        })}
      </ul>
    </Layout>
  )
}

app.get('/', (c) => {
  const messages = ['Good Morning', 'Good Evening', 'Good Night']
  return c.html(<Top messages={messages} />)
})

export default app

フラグメント

フラグメントを使用して、複数の要素を追加ノード無しでグループ化します:

tsx

import { Fragment } from 'hono/jsx'

const List = () => (
  <Fragment>
    <p>first child</p>
    <p>second child</p>
    <p>third child</p>
  </Fragment>
)

きちんと設定されていれば、 <></> を使って書くこともできます。

tsx

const List = () => (
  <>
    <p>first child</p>
    <p>second child</p>
    <p>third child</p>
  </>
)

`PropsWithChildren`

PropsWithChildren を使用すると、関数コンポーネント内の子要素を正しく推論できます。

tsx

import { PropsWithChildren } from 'hono/jsx'

type Post = {
  id: number
  title: string
}

function Component({ title, children }: PropsWithChildren<Post>) {
  return (
    <div>
      <h1>{title}</h1>
      {children}
    </div>
  )
}

生 HTML の挿入

直接 HTML を挿入するには、 dangerouslySetInnerHTML を使用します:

tsx

app.get('/foo', (c) => {
  const inner = { __html: 'JSX &middot; SSR' }
  const Div = <div dangerouslySetInnerHTML={inner} />
})

メモ

memo を使用して、計算済みの文字列を保存することでコンポーネントを最適化します:

tsx

import { memo } from 'hono/jsx'

const Header = memo(() => <header>Welcome to Hono</header>)
const Footer = memo(() => <footer>Powered by Hono</footer>)
const Layout = (
  <div>
    <Header />
    <p>Hono is cool!</p>
    <Footer />
  </div>
)

Context

By using useContext, you can share data globally across any level of the Component tree without passing values through props.

tsx

import type { FC } from 'hono/jsx'
import { createContext, useContext } from 'hono/jsx'

const themes = {
  light: {
    color: '#000000',
    background: '#eeeeee',
  },
  dark: {
    color: '#ffffff',
    background: '#222222',
  },
}

const ThemeContext = createContext(themes.light)

const Button: FC = () => {
  const theme = useContext(ThemeContext)
  return <button style={theme}>Push!</button>
}

const Toolbar: FC = () => {
  return (
    <div>
      <Button />
    </div>
  )
}

// ...

app.get('/', (c) => {
  return c.html(
    <div>
      <ThemeContext.Provider value={themes.dark}>
        <Toolbar />
      </ThemeContext.Provider>
    </div>
  )
})

Async Component

hono/jsx supports an Async Component, so you can use async/await in your component. If you render it with c.html(), it will await automatically.

tsx

const AsyncComponent = async () => {
  await new Promise((r) => setTimeout(r, 1000)) // sleep 1s
  return <div>Done!</div>
}

app.get('/', (c) => {
  return c.html(
    <html>
      <body>
        <AsyncComponent />
      </body>
    </html>
  )
})

Suspense Experimental

The React-like Suspense feature is available. If you wrap the async component with Suspense, the content in the fallback will be rendered first, and once the Promise is resolved, the awaited content will be displayed. You can use it with renderToReadableStream().

tsx

import { renderToReadableStream, Suspense } from 'hono/jsx/streaming'

//...

app.get('/', (c) => {
  const stream = renderToReadableStream(
    <html>
      <body>
        <Suspense fallback={<div>loading...</div>}>
          <Component />
        </Suspense>
      </body>
    </html>
  )
  return c.body(stream, {
    headers: {
      'Content-Type': 'text/html; charset=UTF-8',
      'Transfer-Encoding': 'chunked',
    },
  })
})

ErrorBoundary Experimental

You can catch errors in child components using ErrorBoundary.

In the example below, it will show the content specified in fallback if an error occurs.

tsx

function SyncComponent() {
  throw new Error('Error')
  return <div>Hello</div>
}

app.get('/sync', async (c) => {
  return c.html(
    <html>
      <body>
        <ErrorBoundary fallback={<div>Out of Service</div>}>
          <SyncComponent />
        </ErrorBoundary>
      </body>
    </html>
  )
})

ErrorBoundary can also be used with async components and Suspense.

tsx

async function AsyncComponent() {
  await new Promise((resolve) => setTimeout(resolve, 2000))
  throw new Error('Error')
  return <div>Hello</div>
}

app.get('/with-suspense', async (c) => {
  return c.html(
    <html>
      <body>
        <ErrorBoundary fallback={<div>Out of Service</div>}>
          <Suspense fallback={<div>Loading...</div>}>
            <AsyncComponent />
          </Suspense>
        </ErrorBoundary>
      </body>
    </html>
  )
})

Integration with html Middleware

Combine the JSX and html middlewares for powerful templating. For in-depth details, consult the html middleware documentation.

tsx

import { Hono } from 'hono'
import { html } from 'hono/html'

const app = new Hono()

interface SiteData {
  title: string
  children?: any
}

const Layout = (props: SiteData) =>
  html`<!doctype html>
    <html>
      <head>
        <title>${props.title}</title>
      </head>
      <body>
        ${props.children}
      </body>
    </html>`

const Content = (props: { siteData: SiteData; name: string }) => (
  <Layout {...props.siteData}>
    <h1>Hello {props.name}</h1>
  </Layout>
)

app.get('/:name', (c) => {
  const { name } = c.req.param()
  const props = {
    name: name,
    siteData: {
      title: 'JSX with html sample',
    },
  }
  return c.html(<Content {...props} />)
})

export default app

With JSX Renderer Middleware

The JSX Renderer Middleware allows you to create HTML pages more easily with the JSX.

Override type definitions

You can override the type definition to add your custom elements and attributes.

declare module 'hono/jsx' {
  namespace JSX {
    interface IntrinsicElements {
      'my-custom-element': HTMLAttributes & {
        'x-event'?: 'click' | 'scroll'
      }
    }
  }
}

JSX ​

設定 ​

使い方 ​

フラグメント ​

PropsWithChildren ​

生 HTML の挿入 ​

メモ ​

Context ​

Async Component ​

Suspense Experimental ​

ErrorBoundary Experimental ​

Integration with html Middleware ​

With JSX Renderer Middleware ​

Override type definitions ​

JSX

設定

使い方