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Add pre tag support to paste HTML subset tool #56

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simonw wants to merge 2 commits into from
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Add pre tag support to paste HTML subset tool #56

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5c46914
Add pre tag support to paste HTML subset tool
simonw Oct 3, 2025
c33a5cf
Delete paste-html-subset.docs.md
simonw Oct 3, 2025
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3 changes: 0 additions & 3 deletions paste-html-subset.docs.md
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30 changes: 22 additions & 8 deletions paste-html-subset.html
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Original file line number Diff line number Diff line change
Expand Up @@ -115,7 +115,8 @@ <h3>Supported HTML elements</h3>
<li><strong>strong</strong> - Bold text</li>
<li><strong>em</strong> - Italic text</li>
<li><strong>blockquote</strong> - Quoted text</li>
<li><strong>code</strong> - Code snippets</li>
<li><strong>code</strong> - Inline code snippets</li>
<li><strong>pre</strong> - Preformatted text blocks</li>
<li><strong>a</strong> - Links (href attribute is preserved)</li>
<li><strong>h1-h6</strong> - Headings</li>
<li><strong>ul</strong> - Unordered lists</li>
Expand Down Expand Up @@ -156,7 +157,7 @@ <h2>Preview</h2>
// Function to sanitize HTML and keep only allowed tags and attributes
function sanitizeHtml(html) {
const allowedTags = [
'p', 'strong', 'em', 'blockquote', 'code', 'a',
'p', 'strong', 'em', 'blockquote', 'code', 'pre', 'a',
'h1', 'h2', 'h3', 'h4', 'h5', 'h6',
'ul', 'ol', 'li', 'dl', 'dt', 'dd'
];
Expand Down Expand Up @@ -239,15 +240,22 @@ <h2>Preview</h2>

// Split HTML by tags
const parts = html.split(/(<\/?[^>]+>)/);

const preStack = [];

for (let i = 0; i < parts.length; i++) {
const part = parts[i].trim();
if (!part) continue;

const rawPart = parts[i];
if (!rawPart) continue;

const part = rawPart.trim();
if (!part && preStack.length === 0) continue;

// Check if it's a tag
if (part.startsWith('<')) {
// Closing tag
if (part.startsWith('</')) {
if (/^<\/pre\b/i.test(part) && preStack.length > 0) {
preStack.pop();
}
indent = Math.max(0, indent - 1); // Prevent negative indent
formatted += getIndent(indent) + part + '\n';
}
Expand All @@ -258,15 +266,21 @@ <h2>Preview</h2>
// Opening tag
else {
formatted += getIndent(indent) + part + '\n';
if (/^<pre\b/i.test(part)) {
preStack.push('pre');
}
// Don't increase indent for inline elements
if (!part.match(/<(strong|em|code|a)[^>]*>/i)) {
indent++;
}
}
}
// Content
else if (part) {
formatted += getIndent(indent) + part + '\n';
else {
const content = preStack.length > 0 ? rawPart : part;
if (content || preStack.length > 0) {
formatted += getIndent(indent) + content + '\n';
}
}
}

Expand Down