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MarkdownPreview における HTML の二重パースを解消 #216

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MarkdownPreview における HTML の二重パースを解消 #216

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d9094c8
html の二重パースを解消
kitsne241 Feb 15, 2026
ad4d10a
MarkdownIt インスタンスを共通化してメモリ効率を向上
kitsne241 Feb 15, 2026
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24 changes: 9 additions & 15 deletions src/components/markdown/MarkdownPreview.vue
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
<script setup lang="ts">
import { ref, watch } from 'vue'
import MarkdownIt from 'markdown-it'
import DOMPurify from 'dompurify'
import { md } from '@/utils/markdown'

type HeadingInfo = {
id: string
Expand All @@ -16,11 +16,6 @@ const props = defineProps<{
const headings = defineModel<HeadingInfo[]>('headings')
const htmltext = ref('')

const md = new MarkdownIt({
breaks: true,
linkify: true,
})

// mdtext 変更時に HTML と見出し情報を更新
watch(
() => props.mdtext,
Expand All @@ -29,8 +24,9 @@ watch(
const headingInfos: HeadingInfo[] = []
let idCounter = 0

// DOMPurify を使用して HTML をサニタイズ（script 等を除去）
const cleanHtml = DOMPurify.sanitize(rawHtml, {
// DOMPurify を使用して HTML をサニタイズし、DOM を直接取得
const cleanDom = DOMPurify.sanitize(rawHtml, {
RETURN_DOM: true,
ALLOWED_TAGS: [
'h1',
'h2',
Expand Down Expand Up @@ -61,23 +57,21 @@ watch(
'del',
],
ALLOWED_ATTR: ['class', 'id', 'href'],
})
}) as HTMLElement

// DOM パーサーを使用して安全に見出しを処理
const parser = new DOMParser()
const doc = parser.parseFromString(cleanHtml, 'text/html')
const headingElements = doc.querySelectorAll('h1, h2, h3, h4, h5, h6')
// サニタイズされた DOM から見出しを処理
const headingElements = cleanDom.querySelectorAll('h1, h2, h3, h4, h5, h6')

headingElements.forEach((heading) => {
const level = parseInt(heading.tagName.charAt(1))
const id = `heading-${idCounter++}`
const text = heading.textContent ?? ''
const text = heading.textContent
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Copilot AI Feb 15, 2026

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HeadingInfo.text is typed as string, but heading.textContent is string | null under strict: true. This will either fail type-checking or force downstream handling of null. Consider using a nullish fallback (e.g., heading.textContent ?? '') or updating HeadingInfo.text to allow null if that's intended.

Suggested change
const text = heading.textContent
const text = heading.textContent ?? ''

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@kitsne241 kitsne241 Feb 15, 2026

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strict: true の場合にも heading.textContent は string と型推論され、null にはなりえません。heading 自体が Element として型推論されているからです


heading.setAttribute('id', id)
headingInfos.push({ id, level, text })
})

htmltext.value = doc.body.innerHTML
htmltext.value = cleanDom.innerHTML
headings.value = headingInfos
},
{ immediate: true },
Expand Down
7 changes: 7 additions & 0 deletions src/utils/markdown.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
import MarkdownIt from 'markdown-it'

// 再利用可能な MarkdownIt インスタンス
export const md = new MarkdownIt({
breaks: true,
linkify: true,
})