Showing the inconsistent behavior and a much better alternative

typeofHell.js

console.log(typeof "foo" === "string"); //true 
console.log(typeof String("foo") === "string"); // true
console.log(typeof new String("foo") === "string"); // false
console.log(typeof 1.2 === "number"); //true
console.log(typeof new Date() === "Date"); //false Date is an Object
console.log(typeof [1,2,3] === "array"); //false, an array is on object!

/** Proper way to test type of object **/

function is(type, obj) {
    var clas = Object.prototype.toString.call(obj).slice(8, -1);
    return obj !== undefined && obj !== null && clas === type;
}

console.log(is('String', 'test')); // true
console.log(is('String', new String('test'))); // true
console.log(is('Date', new Date())); // true