https://tidyverse.org/js/math-code.js

1(function() {
2  var i, text, code, codes = document.getElementsByTagName('code');
3  for (i = 0; i < codes.length;) {
4    code = codes[i];
5    if (code.parentNode.tagName !== 'PRE' && code.childElementCount === 0) {
6      text = code.textContent;
7      if (/^\$[^$]/.test(text) && /[^$]\$$/.test(text)) {
8        text = text.replace(/^\$/, '\\(').replace(/\$$/, '\\)');
9        code.textContent = text;
10      }
11      if (/^\\\((.|\s)+\\\)$/.test(text) || /^\\\[(.|\s)+\\\]$/.test(text) ||
12          /^\$(.|\s)+\$$/.test(text) ||
13          /^\\begin\{([^}]+)\}(.|\s)+\\end\{[^}]+\}$/.test(text)) {
14        code.outerHTML = code.innerHTML;  // remove <code></code>
15        continue;
16      }
17    }
18    i++;
19  }
20})();