code: function is(obj, clazz) {
          return Object.prototype.toString.call(obj).slice(8, -1) === clazz;
      }
docs: /* See link for possible type values to check against.
  http://stackoverflow.com/questions/4622952/json-object-containing-array
  
  Value               Class      Type
  -------------------------------------
  "foo"               String     string
  new String("foo")   String     object
  1.2                 Number     number
  new Number(1.2)     Number     object
  true                Boolean    boolean
  new Boolean(true)   Boolean    object
  new Date()          Date       object
  new Error()         Error      object
  [1,2,3]             Array      object
  new Array(1, 2, 3)  Array      object
  new Function("")    Function   function
  /abc/g              RegExp     object (function in Nitro/V8)
  new RegExp("meow")  RegExp     object (function in Nitro/V8)
  {}                  Object     object
  new Object()        Object     object