getUniqueKeys.js

  function getKeys(obj) {
    if (Object.prototype.toString.call(obj) !== "[object Object]") return;
    return recurse(obj, []);
    function recurse(obj, tmp) {
      for (var p in obj) {
        if (tmp.indexOf(p) === -1) tmp.push(p);
        if (Object.prototype.toString.call(obj[p]) === "[object Object]") recurse(obj[p], tmp);
      }
      return tmp;
    }
  }