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ellen364 opened this issue Mar 26, 2023 · 2 comments · Fixed by #5835
Closed

Previews don't have doctype, causing browsers to use quirks mode #5828

ellen364 opened this issue Mar 26, 2023 · 2 comments · Fixed by #5835

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@ellen364
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ellen364 commented Mar 26, 2023 •
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The preview HTML generated by the experimental Sandpack bundler doesn't include a DOCTYPE, causing browsers to use Quirks Mode.

To reproduce, go to any page with previews (e.g. /learn)

  • Firefox (v111.0) Open console and see the warning about Quirks Mode
  • Chrome (v111.0.5563.110) Open dev tools, select an iframe, in console run document.compatMode, which returns "BackCompat"
  • Safari (v16.3) Same as Chrome

When using the experimental bundler, the HTML in the iframes is minimal, e.g.

<html>
  <head>
    <title>Sandpack Preview</title>
    <meta charset="utf-8">
    <style id="/styles.css-css" type="text/css"><!-- styles omitted --></style>
  </head>
  <body>
    <div id="root">
      <div>
        <h1>Welcome to my app</h1>
        <button>I'm a button</button>
      </div>
    </div>
  </body>
</html>

Running the code locally, commenting out the bunderUrl in src/components/MDX/Sandpack/SandpackRoot produces fuller HTML:

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>Sandbox - CodeSandbox</title>
    <link rel="manifest" href="/manifest.json">
    <link href="data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'>
      <style>
<!-- styles omitted -->
      </style>
      <path fill-rule='evenodd' clip-rule='evenodd' d='M81.8182 18.1818V81.8182H18.1818V18.1818H81.8182ZM10 90V10H90V90H10Z'/>
      </svg>" rel="icon">
    <link rel="mask-icon" href="/csb-ios.svg" color="#fff">
    <script src="/static/browserfs12/browserfs.min.js" type="text/javascript"></script><script>window.process=BrowserFS.BFSRequire("process"),window.Buffer=BrowserFS.BFSRequire("buffer").Buffer</script>
    <link href="/static/js/babel.7.12.12.min.js" rel="prefetch" as="script">
    <style id="/styles.css:-css" type="text/css"><!-- styles omitted --></style>
    <script charset="utf-8" src="/static/js/2.61b71a6f1.chunk.js"></script><script charset="utf-8" src="/static/js/6.2298658e4.chunk.js"></script>
  </head>
  <body>
    <div id="root">
      <div>
        <h1>Welcome to my app</h1>
        <button>I'm a button</button>
      </div>
    </div>
  </body>
</html>

Despite the length of HTML produced by the old bundler, the only major things missing seem to be doctype and viewport.

Presumably this is a bug in Sandpack's new bundler, which was added to the React docs in #4458

That PR mentions expected performance improvements, so this might be a temporary trade off between performance and compatibility. I didn't see Quirks Mode mentioned anywhere, though, and seemed worth raising an issue.
@ellen364
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I've proposed a fix in codesandbox/sandpack-bundler#51

@gaearon
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gaearon commented Mar 27, 2023

Nice catch!

@DeMoorJasper DeMoorJasper mentioned this issue Mar 28, 2023
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chore: update bundlerUrl DeMoorJasper/reactjs.org
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@gaearon @ellen364