Frontends (.ui folder)

The standard behavior of hyper:// is to serve whichever file is referenced by the URL. This works fine for simple use-cases, but struggles with two use-cases:

  1. Sites which need a consistent theme and template applied across each page.

  2. Applications which need to serve interfaces even where a file does not exist (as in the Single Page Application pattern).

Two solve this, the hyper:// protocol supports a behavior called "Frontends."

How frontends work

A Frontend is simply an html file found at /.ui/ui.html. This file is used to provide a consistent interface for the site. It is served rather than the target file in the following cases:

  • No file exists at the target URL.

  • The target URL is a folder.

  • The "Accept" header includes text/html (which indicates the browser is asking for a "page").

Because the Frontend effectively overrides all page-serving, it can render whatever the site author wants. A common pattern is to use JavaScript to read whatever file is referenced by window.location.pathname and then place that in the UI, as in this example snippet:

/.ui/ui.html
<body>
  <main></main>
</body>
<script>
async function setup () {
  var main = document.querySelector('main')
  if (location.pathname.endsWith('.html')) {
    let self = new Hyperdrive(location.hostname)
    let html = await self.readFile(location.pathname).catch(e => `<h1>404 not found<h1>`)
    main.innerHTML = html
  } else if (location.pathname.endsWith('.jpg')) {
    main.innerHTML = `<img src="${location.pathname}">`
  } // etc...
}
setup()
</script>

Mounted frontends

An advantage of Frontends is that they are stored in a subfolder. This makes it possible for frontends to be their own Hyperdrive sites which are mounted to /.ui.

|12345..af> mount $my_frontend_drive_url /.ui

Frontend hyperdrives can then be published and shared across multiple sites.

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