All JSON compatible (and incompatible thanks to "function") types in a simple cross platform function

type.js

var type = function (isArray, type){
  return function(object) {
    type = typeof object;
    return type === "object" ? (
      object ? (
        isArray(object) ? "array" : type
      ) : "null"
    ) : type;
  };
}(Array.isArray || function(Array, toString, array){
  array = toString.call([]);
  return function(object) {
    return (
      object instanceof Array ||
      toString.call(object) === array
    );
  }
}(Array, {}.toString));

to test above snippet:

alert([
  type(""),          // string
  type(1),           // number
  type({}),          // object
  type([]),          // array
  type(true),        // boolean
  type(false),       // boolean
  type(null),        // null
  type(),            // undefined
  type(function(){}) // function
].join("\n"));