Function escape

docs/js/marked.js:978–985

* Helpers

(html, encode)

 */

function escape(html, encode) {
  return html
    .replace(!encode ? /&(?!#?\w+;)/g : /&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

function replace(regex, opt) {
  regex = regex.source;