This does unescape &#xHHHH; \uHHHH on HTML/JSON/YAML etc. An Unicode escape decoder.

unescape.js

var cache = {};
var regex = /\\u[0-9a-f]{4}|\&(\w+|\#([0-9]+|x[0-9a-f]+))\;/g;
var ignore = /[\x00-\x20\>\<\&\"\']/;
var func = function (match) {
  var ret = cache[match];
  if (! ret) {
    var head = match.charAt(0);
    if (head == "&") {
      var p = document.createElement("p");
      p.innerHTML = match;
      ret = p.firstChild ? p.firstChild.data : match;
    } else {
      var src = match.substr(2, 4);
      var cd = parseInt(src, 16);
      ret = String.fromCharCode(cd);
    }
    if (ret.match(ignore)) ret = match;
    cache[match] = ret;
  }
  return ret;
};

var walker = document.createTreeWalker(document.body, NodeFilter.SHOW_TEXT);
while(walker.nextNode()) {
  var src = walker.currentNode.data;
  if (! src) continue;
  var dst = src.replace(regex, func);
  if (src != dst) walker.currentNode.data = dst;
}

unescape - ページ中の&#xHHHH;や\uHHHHのエスケープを展開するブックマークレット
http://kawanet.hatenablog.com/entry/20121120/1353402584