MJML postrender fix

postrender.js

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
var removeCDATA = exports.removeCDATA = function removeCDATA(str) {
  return str.replace(/(?:<!-{0,2}\[CDATA\[){1,2}([^]*?)(?:\]\]-{0,2}>?){1,2}/gm, '$1');
};

var fixLegacyAttrs = exports.fixLegacyAttrs = function fixLegacyAttrs($) {
  var legacyAttrs = ['align', 'valign', 'bgcolor', 'border', 'background'];

  // https://github.com/facebook/react/issues/140 ...
  // server side workaround to allow custom tags.
  legacyAttrs.forEach(function (attr) {
    var dataAttr = 'data-legacy-' + attr;

    $('[' + dataAttr + ']').each(function () {
      $(this).attr(attr, $(this).attr(dataAttr));
      $(this).removeAttr(dataAttr);
    });
  });

  return $;
};

Some component may be parsed twice, seeing their content twice embedded between CDATA tags, e.g.

<!--[CDATA[<![CDATA[
    <script></script>
    <style>
@media all {
  a.link:hover {
    text-decoration: underline !important;
  }
}
</style>
        <script type="application/ld+json">
            {
                "@context": "http://schema.org",
                "@type": "EmailMessage",
                "potentialAction": {
                    "@type": "ViewAction",
                    "name": "{{saveto.name}}",
                    "target": "{{saveto.link}}",
                    "url": "{{saveto.link}}"
                },
                "description": "{{saveto.description}}"
            }
        </script>    ]]-->]]

… Which, once it gets through postrender will still have one remaining CDATA or ]] artefact.
The key is to collect both regular CDATA tags and multiple concatenation. At the time of writing, I didn't find any case with more than two consecutive CDATAs.

Before/after

/<!--\[CDATA\[([^]*?)\]\]-->/gm

/(?:<!-{0,2}\[CDATA\[){1,2}([^]*?)(?:\]\]-{0,2}>?){1,2}/gm