typeOf.js

var typeOf = (function(Object, RegExp){
  // WTFPL License - http://en.wikipedia.org/wiki/WTFPL
  // thanks to @jdalton and @ljharb
  var toString = Object.prototype.toString,
      cache = (Object.create || Object)(null);
  return function typeOf(Unknown) {
    var asString = typeof Unknown;
    return asString == 'object' ? (
      Unknown === null ? 'null' : (
        cache[asString = toString.call(Unknown)] || (
          cache[asString] = asString
            .slice(asString.indexOf(' ') + 1, -1)
            .toLowerCase()
        )
      )
    ) : asString;
  };
}(Object, RegExp));