"use strict";
var pruMD = require('./pru-md.js');
var hljs       = require('highlight.js'); // https://highlightjs.org/ 
var showdown  = require('showdown');
var converter = new showdown.Converter();

var extHL = function () {
  var myext1 = {
    type: 'output',
    regex: /markdown/g,
    replace: 'showdown'
  };
  return [myext1];
}

pruMD.probar({parse : function(content) { return converter.makeHtml(content); },
              name : function() { return 'showdown'; }}).then(function(out) { console.log(out); });

Y una tabla