afd68e5674
This is based on a discussion we had a few weeks ago. Currently if a component uses `ViewEncapsulation.ShadowDom` and its selector doesn't meet the requirements for a custom element tag name, a vague error will be thrown at runtime saying something like "Element does not support attachShadowRoot". These changes add a new diagnostic to the compiler that validates the component selector and gives a better error message during compilation. PR Close #42245
33 lines
735 B
Markdown
33 lines
735 B
Markdown
@name Invalid Shadow DOM selector
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@category compiler
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@shortDescription Component selector does not match shadow DOM requirements
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@description
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The selector of a component using `ViewEncapsulation.ShadowDom` doesn't match the custom element tag name requirements.
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In order for a tag name to be considered a valid custom element name, it has to:
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* Be in lower case.
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* Contain a hyphen.
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* Start with a letter (a-z).
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@debugging
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Rename your component's selector so that it matches the requirements.
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**Before:**
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```typescript
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@Component({
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selector: 'comp',
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encapsulation: ViewEncapsulation.ShadowDom
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...
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})
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```
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**After:**
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```typescript
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@Component({
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selector: 'app-comp',
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encapsulation: ViewEncapsulation.ShadowDom
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...
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})
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```
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