fix: convert apps/website from submodule to regular directory

2026-07-16 01:42:45 +08:00
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+---
+title: In-DOM Template Parsing Caveats
+impact: HIGH
+impactDescription: Browser HTML parsing before Vue compilation causes case sensitivity, self-closing tag, and element nesting issues
+type: gotcha
+tags: [vue3, templates, in-dom, html-parsing, kebab-case, self-closing-tags]
+---
+
+# In-DOM Template Parsing Caveats
+
+**Impact: HIGH** - When writing Vue templates directly in the DOM (not in `.vue` files), the browser's native HTML parser processes the template BEFORE Vue sees it. This causes three critical issues: case sensitivity problems, self-closing tag failures, and element placement restrictions.
+
+These issues do NOT apply to Single-File Components (SFCs) or string templates where Vue's compiler handles parsing directly.
+
+## Task Checklist
+
+- [ ] Use kebab-case for component names in in-DOM templates
+- [ ] Use kebab-case for prop names in in-DOM templates
+- [ ] Use explicit closing tags (not self-closing) in in-DOM templates
+- [ ] Use `is="vue:component-name"` for components inside restricted elements
+- [ ] Prefer SFCs to avoid all in-DOM parsing issues
+
+## Issue 1: Case Insensitivity
+
+HTML is case-insensitive. The browser lowercases everything before Vue sees it.
+
+**Incorrect (in-DOM template):**
+```html
+<!-- Browser converts to: <blogpost posttitle="hello"> -->
+<BlogPost postTitle="hello" @updatePost="onUpdate"></BlogPost>
+```
+
+**Correct (in-DOM template):**
+```html
+<!-- Use kebab-case for everything -->
+<blog-post post-title="hello" @update-post="onUpdate"></blog-post>
+```
+
+**In SFCs, PascalCase works fine:**
+```vue
+<!-- BlogPost.vue - PascalCase recommended -->
+<template>
+  <BlogPost postTitle="hello" @updatePost="onUpdate" />
+</template>
+```
+
+## Issue 2: Self-Closing Tags Fail
+
+HTML only allows self-closing syntax for void elements (`<input>`, `<img>`, etc.). For all others, the browser expects closing tags.
+
+**Incorrect (in-DOM template):**
+```html
+<!-- Browser thinks the tag never closed, breaks nesting -->
+<my-component />
+<another-component />
+```
+
+**Correct (in-DOM template):**
+```html
+<!-- Explicit closing tags required -->
+<my-component></my-component>
+<another-component></another-component>
+```
+
+**In SFCs, self-closing works fine:**
+```vue
+<template>
+  <MyComponent />
+  <AnotherComponent />
+</template>
+```
+
+## Issue 3: Element Placement Restrictions
+
+Some HTML elements have strict rules about valid children. Invalid elements are hoisted out by the browser before Vue sees the template.
+
+**Restricted parent elements:**
+- `<ul>`, `<ol>` - only allow `<li>`
+- `<table>` - only allows `<thead>`, `<tbody>`, `<tfoot>`, `<tr>`, `<caption>`, `<colgroup>`
+- `<tr>` - only allows `<td>`, `<th>`
+- `<select>` - only allows `<option>`, `<optgroup>`
+
+**Incorrect (in-DOM template):**
+```html
+<!-- Browser hoists blog-post-row outside the table -->
+<table>
+  <blog-post-row v-for="post in posts" :post="post"></blog-post-row>
+</table>
+
+<!-- Renders as: -->
+<blog-post-row></blog-post-row>
+<blog-post-row></blog-post-row>
+<table></table>
+```
+
+**Correct (in-DOM template):**
+```html
+<!-- Use is="vue:component-name" on a valid native element -->
+<table>
+  <tr is="vue:blog-post-row" v-for="post in posts" :key="post.id" :post="post"></tr>
+</table>
+```
+
+```html
+<ul>
+  <li is="vue:todo-item" v-for="todo in todos" :key="todo.id" :todo="todo"></li>
+</ul>
+```
+
+**Important:** The `vue:` prefix is required! Without it, `is` is treated as a native customized built-in element attribute.
+
+```html
+<!-- WRONG: Missing vue: prefix -->
+<tr is="blog-post-row"></tr>
+
+<!-- CORRECT: With vue: prefix -->
+<tr is="vue:blog-post-row"></tr>
+```
+
+## When Do These Apply?
+
+| Template Type | Affected? | Example |
+|---------------|-----------|---------|
+| Single-File Component (`.vue`) | No | `<template>` section |
+| String template | No | `template: '<div>...</div>'` |
+| In-DOM template | **Yes** | `<div id="app">...</div>` |
+| `<script type="text/x-template">` | **Yes** | Browser parses the script content |
+
+## Best Practice: Use SFCs
+
+The simplest solution is to use Single-File Components (`.vue` files) which completely avoid in-DOM parsing issues:
+
+```vue
+<!-- MyComponent.vue - All issues avoided -->
+<script setup>
+import BlogPost from './BlogPost.vue'
+</script>
+
+<template>
+  <BlogPost postTitle="hello" @updatePost="onUpdate" />
+
+  <table>
+    <BlogPostRow v-for="post in posts" :key="post.id" :post="post" />
+  </table>
+</template>
+```
+
+## Reference
+- [Vue.js - In-DOM Template Parsing Caveats](https://vuejs.org/guide/essentials/component-basics.html#in-dom-template-parsing-caveats)