showdownjs/showdown

/**
 * Within tags -- meaning between < and > -- encode [\ ` * _ ~ =] so they
 * don't conflict with their use in Markdown for code, italics and strong.
 */
showdown.subParser('makehtml.escapeSpecialCharsWithinTagAttributes', function (text, options, globals) {
  'use strict';
  text = globals.converter._dispatch('makehtml.escapeSpecialCharsWithinTagAttributes.before', text, options, globals).getText();

  // Build a regex to find HTML tags.
  var tags     = /<\/?[a-z\d_:-]+(?:[\s]+[\s\S]+?)?>/gi,
      comments = /<!(--(?:(?:[^>-]|-[^>])(?:[^-]|-[^-])*)--)>/gi;

  text = text.replace(tags, function (wholeMatch) {
    return wholeMatch
      .replace(/(.)<\/?code>(?=.)/g, '$1`')
      .replace(/([\\`*_~=|])/g, showdown.helper.escapeCharactersCallback);
  });

  text = text.replace(comments, function (wholeMatch) {
    return wholeMatch
      .replace(/([\\`*_~=|])/g, showdown.helper.escapeCharactersCallback);
  });

  text = globals.converter._dispatch('makehtml.escapeSpecialCharsWithinTagAttributes.after', text, options, globals).getText();
  return text;
});