67 lines
1.9 KiB
TypeScript
67 lines
1.9 KiB
TypeScript
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/**
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* Lazy KaTeX math rendering for markdown content.
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* Detects $...$ (inline) and $$...$$ (block) LaTeX.
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* Falls back to raw <code> on invalid LaTeX.
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*/
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let katexModule: typeof import('katex') | null = null
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let katexLoading: Promise<typeof import('katex')> | null = null
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async function loadKaTeX() {
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if (katexModule) return katexModule
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if (katexLoading) return katexLoading
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katexLoading = import('katex').then((m) => {
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katexModule = m
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// Inject KaTeX CSS
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if (!document.getElementById('katex-css')) {
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const link = document.createElement('link')
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link.id = 'katex-css'
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link.rel = 'stylesheet'
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link.href = new URL('katex/dist/katex.min.css', import.meta.url).toString()
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document.head.appendChild(link)
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}
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return m
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})
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return katexLoading
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}
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const BLOCK_RE = /\$\$([\s\S]+?)\$\$/g
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const INLINE_RE = /\$([^\n$]+?)\$/g
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function renderKaTeX(latex: string, displayMode: boolean): string {
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if (!katexModule) return `<code>${escapeForHtml(latex)}</code>`
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try {
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return katexModule.default.renderToString(latex, {
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displayMode,
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throwOnError: false,
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output: 'html',
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})
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} catch {
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return `<code>${escapeForHtml(latex)}</code>`
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}
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}
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function escapeForHtml(s: string): string {
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return s.replace(/&/g, '&').replace(/</g, '<').replace(/>/g, '>')
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}
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export function hasMath(text: string): boolean {
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return /\$\$[\s\S]+?\$\$/.test(text) || /\$[^\n$]+?\$/.test(text)
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}
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export async function renderMathInHtml(html: string): Promise<string> {
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await loadKaTeX()
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// Block math first ($$...$$)
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let result = html.replace(BLOCK_RE, (_, latex) => {
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return `<div class="katex-block my-4 text-center overflow-x-auto">${renderKaTeX(latex.trim(), true)}</div>`
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})
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// Inline math ($...$)
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result = result.replace(INLINE_RE, (_, latex) => {
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return renderKaTeX(latex.trim(), false)
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})
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return result
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}
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