gistfile1.txt

markup.doc = document.implementation.createHTMLDocument ? document.implementation.createHTMLDocument("") : null;

function markup(s) {
  var doc = markup.doc;
  var div = null;
  if (doc === null) {
    div = document.createElement("div");
    if (window.toStaticHTML) {// IE 8
      div.innerHTML = window.toStaticHTML(s);
    } else {
      div.appendChild(document.createTextNode(s));
    }
  } else {
    div = doc.createElement("div");
    div.innerHTML = s;
  }
  var whiteList = ["A", "ABBR", "ADDRESS", "ARTICLE", "ASIDE", "B", "BDO", "BLOCKQUOTE", "BR", "CAPTION", "CITE", "CODE", "COLGROUP", "DATA", "DD", "DEL", "DFN", "DIV", "DL", "DT", "EM", "FIGCAPTION", "FIGURE", "H1", "H2", "H3", "H4", "H5", "H6", "HR", "I", "INS", "KBD", "LI", "MARK", "NAV", "OL", "P", "PRE", "Q", "RP", "RT", "RUBY", "S", "SAMP", "SECTION", "SMALL", "SPAN", "STRONG", "SUB", "SUP", "TABLE", "TBODY", "TD", "TFOOT", "TH", "THEAD", "TIME", "TR", "U", "UL", "VAR", "WBR"];
  var attributesWhiteList = ["title"];
  var attributesToRemove = [];
  var walk = function (element) {
    var child = element.firstChild;
    while (child !== null) {
      var next = child.nextSibling;
      var nodeType = child.nodeType;
      var allowElement = true;
      if (nodeType !== Node.TEXT_NODE) {
        if (nodeType === Node.ELEMENT_NODE) {
          var tagName = child.tagName;
          var allowElement = whiteList.indexOf(tagName) !== -1;
          var allowedAttributes = attributesWhiteList;
          if (tagName === "A") {
            if (/^(data|blob|javascript)\:$/i.test(child.protocol)) {
              allowElement = false;
            }
            allowedAttributes = ["href", "title"];
          }
          if (allowElement) {
            var attributes = child.attributes;
            var i = attributes.length;
            while (--i >= 0) {
              var attribute = attributes[i];
              var name = attribute.name;
              if (allowedAttributes.indexOf(name) === -1) {//TODO: indexOf
                attributesToRemove.push(name);
              }
            }
            i = attributesToRemove.length;
            while (--i >= 0) {
              child.removeAttribute(attributesToRemove[i]);
            }
            attributesToRemove.length = 0;
          }
          if (allowElement) {
            walk(child);
          }
        } else {
          allowElement = false;
        }
      } else {
        var span = document.createElement("span");
        span.innerHTML = autoLink(child.nodeValue);
        element.replaceChild(span, child);
      }
      if (!allowElement) {
        element.removeChild(child);
      }
      child = next;
    }
  };
  walk(div);
  return div;
}