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// NymDrop — minimal self-hosted Markdown preview for the message field.
// No external library: a small, auditable subset is enough for a
// submission form, and it avoids pulling a third-party JS dependency into
// a page whose whole point is minimizing trust in client-side code.
//
// The rendered HTML never leaves the browser — the encrypted submission
// still carries the raw Markdown source text untouched (see app.js). This
// is purely a "what will this look like" aid for the person writing it.
function mdEscapeHtml(str) {
return str
.replace(/&/g, "&")
.replace(/</g, "<")
.replace(/>/g, ">")
.replace(/"/g, """)
.replace(/'/g, "'");
}
// Only allow link schemes that can't execute script in the rendered preview.
function mdSafeHref(url) {
if (/^(https?:|mailto:)/i.test(url)) return mdEscapeHtml(url);
return "#";
}
function mdInline(text) {
let out = mdEscapeHtml(text);
out = out.replace(/`([^`]+)`/g, "<code>$1</code>");
out = out.replace(/\*\*([^*]+)\*\*|__([^_]+)__/g, (m, a, b) => `<strong>${a || b}</strong>`);
out = out.replace(/\*([^*]+)\*|_([^_]+)_/g, (m, a, b) => `<em>${a || b}</em>`);
out = out.replace(/\[([^\]]+)\]\(([^)\s]+)\)/g, (m, label, url) =>
`<a href="${mdSafeHref(url)}" target="_blank" rel="noopener noreferrer">${label}</a>`);
return out;
}
function renderMarkdown(source) {
const lines = source.replace(/\r\n/g, "\n").split("\n");
const html = [];
let i = 0;
let para = [];
function flushPara() {
if (para.length) {
html.push("<p>" + para.map(mdInline).join("<br>") + "</p>");
para = [];
}
}
while (i < lines.length) {
const line = lines[i];
if (/^```/.test(line)) {
flushPara();
const code = [];
i++;
while (i < lines.length && !/^```/.test(lines[i])) {
code.push(lines[i]);
i++;
}
html.push("<pre><code>" + mdEscapeHtml(code.join("\n")) + "</code></pre>");
i++;
continue;
}
const heading = line.match(/^(#{1,3})\s+(.*)$/);
if (heading) {
flushPara();
const level = heading[1].length;
html.push(`<h${level}>${mdInline(heading[2])}</h${level}>`);
i++;
continue;
}
if (/^(---|\*\*\*)\s*$/.test(line)) {
flushPara();
html.push("<hr>");
i++;
continue;
}
if (/^>\s?/.test(line)) {
flushPara();
const quote = [];
while (i < lines.length && /^>\s?/.test(lines[i])) {
quote.push(lines[i].replace(/^>\s?/, ""));
i++;
}
html.push("<blockquote>" + renderMarkdown(quote.join("\n")) + "</blockquote>");
continue;
}
if (/^[-*]\s+/.test(line)) {
flushPara();
const items = [];
while (i < lines.length && /^[-*]\s+/.test(lines[i])) {
items.push(`<li>${mdInline(lines[i].replace(/^[-*]\s+/, ""))}</li>`);
i++;
}
html.push("<ul>" + items.join("") + "</ul>");
continue;
}
if (/^\d+\.\s+/.test(line)) {
flushPara();
const items = [];
while (i < lines.length && /^\d+\.\s+/.test(lines[i])) {
items.push(`<li>${mdInline(lines[i].replace(/^\d+\.\s+/, ""))}</li>`);
i++;
}
html.push("<ol>" + items.join("") + "</ol>");
continue;
}
if (line.trim() === "") {
flushPara();
i++;
continue;
}
para.push(line);
i++;
}
flushPara();
return html.join("\n");
}
(function() {
const textarea = document.getElementById("message");
const preview = document.getElementById("message-preview");
const toggle = document.getElementById("preview-toggle");
if (!textarea || !preview || !toggle) return;
let showingPreview = false;
toggle.addEventListener("click", function() {
showingPreview = !showingPreview;
if (showingPreview) {
preview.innerHTML = renderMarkdown(textarea.value) ||
'<p class="md-empty">Nothing to preview yet.</p>';
textarea.hidden = true;
preview.hidden = false;
toggle.textContent = "Edit";
} else {
preview.hidden = true;
textarea.hidden = false;
toggle.textContent = "Preview";
}
});
})();
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