Object and String prototypes are not prototypes of defined strings?

Question

I\'m trying to understand how JavaScript\'s prototype-based inheritance works. I was expecting the below outputs would evaluate as true. Why is this?

Answer 1

Basically, isPrototypeOf only works on objects, and string primitives are not objects, they are primitives.

If you were using the String wrapper object, it would work (but don't do that!):

var myStr = new String("Sample");
console.log(String.prototype.isPrototypeOf(myStr)); // true
console.log(Object.prototype.isPrototypeOf(myStr)); // true

But the wrapper objects are generally bad practice, so don't use them.

Alternately, you could cast them to their object form when testing.

var myStr = "Sample";
console.log(String.prototype.isPrototypeOf(Object(myStr))); // true
console.log(Object.prototype.isPrototypeOf(Object(myStr))); // true