delete in removeAttribute causes TypeError about diffhtml HOT 7 CLOSED

Released in https://github.com/tbranyen/diffhtml/releases/tag/v1.0.0-beta.27

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Fix opened here @CetinSert #262

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Can you post an example of what is breaking? The first delete is not in a try/catch intentionally for performance reasons. This code attempts to delete a property and if it succeeds, marks that property as safe for a given tag name. That's the only way the first delete will be reached.

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Here is an absolutely minimal case: https://tw.uido.co/test/index.html

<script src="//webpdf.co/<>" type=module></script>

<pdf-file id=f src=//pdf.ist/web.pdf></pdf-file>
<div      id=i><pdf-page off=f></pdf-page></div>

<script type=module>
  import * as diff from '//esm.run/diffhtml'; window.diff = diff;
  await customElements.whenDefined('pdf-page');
  await diff.innerHTML(i, `<pdf-page of=f></pdf-page>`);  // patch.js     setAttribute  does allowlist.add(blocklistName)
  await diff.innerHTML(i, `<pdf-page off=f></pdf-page>`); // patch.js removeAttribute checks allowlist TypeError
</script>

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The of attribute is defined using Object.defineProperty (with configurable set to false; as is default).

So of

• can be set (setAttribute extends allowlist)
  

  diffhtml/packages/diffhtml/lib/node/patch.js

  Line 53 in cab7fb3

  allowlist.add(blocklistName);

  
  but
  
  
• cannot be deleted (removeAttribute check same allowlist)
  https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Cant_delete#examples
  https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty#configurable
  

  diffhtml/packages/diffhtml/lib/node/patch.js

  Lines 92 to 94 in cab7fb3

  	if (allowlist.has(blocklistName)) {
  	anyNode[name] = undefined;
  	delete anyNode[name];

setAttribute and removeAttribute would need different

• allowlists
  or
  
• blocklistNames

for HTML custom elements that define attribute ↔ property mirroring via Object.defineProperty.

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@tbranyen – I have demoed and described the problem/solution in the above 2 comments.

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Darnit, so my Travis CI account just ran out of open source credits. The credits should reset in an hour and a half when the new month starts. Would be awesome to convert this project to GitHub Actions CI infra instead.

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