从零写一个 Markdown 解析器：够用就好

function render(src) {
  var lines = src.replace(/\r\n/g, "\n").split("\n");
  var out = "";
  var i = 0;

  while (i < lines.length) {
    // 1. 围栏代码块：整块吞掉，内部不再解析
    // 2. 标题
    // 3. 引用块
    // 4. 表格
    // 5. 列表（递归处理缩进）
    // 6. 分隔线
    // 7. 空行：结束当前段落
    // 8. 其他：普通段落
  }
  return out;
}

function escapeHtml(s) {
  return String(s)
    .replace(/&/g, "&")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;");
}

// 行内解析：先转义，再套 Markdown 语法
function inline(text) {
  var s = escapeHtml(text);
  s = s.replace(/`([^`]+)`/g, "<code>$1</code>");
  s = s.replace(/\*\*([^*]+)\*\*/g, "<strong>$1</strong>");
  return s;
}

function safeUrl(u) {
  var t = String(u).trim();
  return /^(https?:|mailto:|#|\/|\.)/i.test(t) ? t : "#";
}
// 挡掉 javascript: 伪协议

if (/^\s*```/.test(lines[i])) {
  var lang = lines[i].replace(/^\s*```/, "").trim();
  var buf = [];
  i++;
  while (i < lines.length && !/^\s*```/.test(lines[i])) {
    buf.push(lines[i]);
    i++;
  }
  i++;   // 跳过结束围栏
  out += codeBlock(buf.join("\n"), lang);
  continue;
}

// 收集
var items = [];
while (i < lines.length) {
  var m = lines[i].match(/^(\s*)([-*+]|\d+[.)])\s+(.+)$/);
  if (!m) break;
  items.push({
    indent: m[1].length,
    ordered: /\d/.test(m[2]),
    text: m[3]
  });
  i++;
}

// 递归构建
function buildList(items, idx, indent) {
  var ordered = items[idx].ordered;
  var html = ordered ? "<ol>" : "<ul>";
  while (idx < items.length) {
    var it = items[idx];
    if (it.indent < indent) break;
    if (it.indent > indent) {
      // 更深的缩进：递归，把结果塞进上一个 <li>
      var sub = buildList(items, idx, it.indent);
      html = html.replace(/<\/li>$/, sub.html + "</li>");
      idx = sub.idx;
      continue;
    }
    html += "<li>" + inline(it.text) + "</li>";
    idx++;
  }
  return { html: html + (ordered ? "</ol>" : "</ul>"), idx: idx };
}

var m = text.match(/^\[([ xX])\]\s+([\s\S]*)$/);
if (m) {
  var done = m[1] !== " ";
  var cls = "task-box" + (done ? " done" : "");
  return "<li class=\"task\"><span class=\"" + cls + "\"></span>"
       + "<span class=\"task-text\">" + inline(m[2]) + "</span></li>";
}

function isTableDelim(line) {
  return /^\s*\|?\s*:?-{2,}:?\s*(\|\s*:?-{2,}:?\s*)*\|?\s*$/.test(line);
}

function splitRow(line) {
  return line.replace(/^\s*\|/, "").replace(/\|\s*$/, "")
             .split("|").map(s => s.trim());
}

var align = cell.trim();
var a = /^:-+:$/.test(align) ? "center"
      : /^-+:$/.test(align) ? "right"
      : /^:-+/.test(align)  ? "left" : "";

function slug(text) {
  return String(text).trim().toLowerCase()
    .replace(/[\s\/]+/g, "-")
    .replace(/[^\w\u4e00-\u9fa5-]/g, "")   // 保留中文、字母、数字、连字符
    .replace(/-+/g, "-")
    .replace(/^-|-$/g, "") || "section";
}

var id = slug(text);
out += "<h" + level + " id=\"" + id + "\">" + inline(text) + "</h" + level + ">";

var buf = [];
while (i < lines.length && lines[i].trim() && !isBlockStart(lines[i])) {
  buf.push(lines[i].trim());
  i++;
}
if (buf.length) out += "<p>" + inline(buf.join(" ")) + "</p>";

node -e "
global.window = {};
require(\"./assets/js/markdown.js\");
require(\"./assets/js/posts.js\");
const MD = window.Markdown;
let bad = 0;
window.POSTS.forEach(p => {
  const h = MD.render(p.content);
  const c = re => (h.match(re) || []).length;
  const errs = [];
  if (c(/<div\\b/g) !== c(/<\\/div>/g)) errs.push(\"div 不配对\");
  if (c(/<pre>/g) !== c(/<\\/pre>/g)) errs.push(\"pre 不配对\");
  if (/undefined/.test(h)) errs.push(\"含 undefined\");
  if (errs.length) { bad++; console.log(p.id, errs); }
});
console.log(bad ? bad + \" 篇异常\" : \"全部通过\");
"