SSG Helper

SSG Helper generates a static site from your Hono application. It will retrieve the contents of registered routes and save them as static files.

Usage

Manual

If you have a simple Hono application like the following:

tsx

// index.tsx
const app = new Hono()

app.get('/', (c) => c.html('Hello, World!'))
app.use('/about', async (c, next) => {
  c.setRenderer((content, head) => {
    return c.html(
      <html>
        <head>
          <title>{head.title ?? ''}</title>
        </head>
        <body>
          <p>{content}</p>
        </body>
      </html>
    )
  })
  await next()
})
app.get('/about', (c) => {
  return c.render('Hello!', { title: 'Hono SSG Page' })
})

export default app

For Node.js, create a build script like this:

// build.ts
import app from './index'
import { toSSG } from 'hono/ssg'
import fs from 'fs/promises'

toSSG(app, fs)

By executing the script, the files will be output as follows:

bash

ls ./static
about.html  index.html

Vite Plugin

Using the @hono/vite-ssg Vite Plugin, you can easily handle the process.

For more details, see here:

https://github.com/honojs/vite-plugins/tree/main/packages/ssg

toSSG

toSSG is the main function for generating static sites, taking an application and a filesystem module as arguments. It is based on the following:

Input

The arguments for toSSG are specified in ToSSGInterface.

export interface ToSSGInterface {
  (app: Hono, fsModule: FileSystemModule, options?: ToSSGOptions): Promise<ToSSGResult>
}

app specifies new Hono() with registered routes.
fs specifies the following object, assuming node:fs/promise.

export interface FileSystemModule {
  writeFile(path: string, data: string | Uint8Array): Promise<void>
  mkdir(path: string, options: { recursive: boolean }): Promise<void | string>
}

Using adapters for Deno and Bun

If you want to use SSG on Deno or Bun, a toSSG function is provided for each file system.

For Deno:

import { toSSG } from 'https://deno.land/x/hono/helper.ts'

toSSG(app) // The second argument is an option typed `ToSSGOptions`.

For Bun:

import { toSSG } from 'hono/bun'

toSSG(app) // The second argument is an option typed `ToSSGOptions`.

Options

Options are specified in the ToSSGOptions interface.

export interface ToSSGOptions {
  dir?: string
  concurrency?: number
  beforeRequestHook?: BeforeRequestHook
  afterResponseHook?: AfterResponseHook
  afterGenerateHook?: AfterGenerateHook
  extensionMap?: Record<string, string>
}

dir is the output destination for Static files. The default value is ./static.
concurrency is the concurrent number of files to be generated at the same time. The default value is 2.
extensionMap is a map containing the Content-Type as a key and the string of the extension as a value. This is used to determine the file extension of the output file.

Each Hook will be described later.

Output

toSSG returns the result in the following Result type.

export interface ToSSGResult {
  success: boolean
  files: string[]
  error?: Error
}

Hook

You can customize the process of toSSG by specifying the following custom hooks in options.

export type BeforeRequestHook = (req: Request) => Request | false
export type AfterResponseHook = (res: Response) => Response | false
export type AfterGenerateHook = (result: ToSSGResult) => void | Promise<void>

BeforeRequestHook/AfterResponseHook

toSSG targets all routes registered in app, but if there are routes you want to exclude, you can filter them by specifying a Hook.

For example, if you want to output only GET requests, filter req.method in beforeRequestHook.

toSSG(app, fs, {
  beforeRequestHook: (req) => {
    if (req.method === 'GET') {
      return req
    }
    return false
  },
})

For example, if you want to output only when StatusCode is 200 or 500, filter res.status in afterResponseHook.

toSSG(app, fs, {
  afterResponseHook: (res) => {
    if (res.status === 200 || res.status === 500) {
      return res
    }
    return false
  },
})

AfterGenerateHook

Use afterGenerateHook if you want to hook the result of toSSG.

toSSG(app, fs, {
  afterGenerateHook: (result) => {
    if (result.files) {
      result.files.forEach((file) => console.log(file))
    }
  })
})

Generate File

Route and Filename

The following rules apply to the registered route information and the generated file name. The default ./static behaves as follows:

/ -> ./static/index.html
/path -> ./static/path.html
/path/ -> ./static/path/index.html

File Extension

The file extension depends on the Content-Type returned by each route. For example, responses from c.html are saved as .html.

If you want to customize the file extensions, set the extensionMap option.

import { toSSG, defaultExtensionMap } from 'hono/ssg'

// Save `application/x-html` content with `.html`
toSSG(app, fs, {
  extensionMap: {
    'application/x-html': 'html',
    ...defaultExtensionMap,
  },
})

Note that paths ending with a slash are saved as index.ext regardless of the extension.

// save to ./static/html/index.html
app.get('/html/', (c) => c.html('html'))

// save to ./static/text/index.txt
app.get('/text/', (c) => c.text('text'))

Middleware

Introducing built-in middleware that supports SSG.

ssgParams

You can use an API like generateStaticPaths of Next.js.

Example:

app.get(
  '/shops/:id',
  ssgParams(async () => {
    const shops = await getShops()
    return shops.map((shop) => ({ id: shop.id }))
  }),
  async (c) => {
    const shop = await getShop(c.req.param('id'))
    if (!shop) {
      return c.notFound()
    }
    return c.render(
      <div>
        <h1>{shop.name}</h1>
      </div>
    )
  }
)

disableSSG

Routes with the disableSSG middleware set are excluded from static file generation by toSSG.

app.get('/api', disableSSG(), (c) => c.text('an-api'))

onlySSG

Routes with the onlySSG middleware set will be overridden by c.notFound() after toSSG execution.

app.get('/static-page', onlySSG(), (c) => c.html(<h1>Welcome to my site</h1>))

SSG Helper ​

Usage ​

Manual ​

Vite Plugin ​

toSSG ​

Input ​

Using adapters for Deno and Bun ​

Options ​

Output ​

Hook ​

BeforeRequestHook/AfterResponseHook ​

AfterGenerateHook ​

Generate File ​

Route and Filename ​

File Extension ​

Middleware ​

ssgParams ​

disableSSG ​

onlySSG ​