Javascript中的String构造函数如何返回没有键的Object？

Question

When I do new String("hello") in my console I get the following result:

String {"hello", length: 5}

The first value in the String Object that was returned doesn't have a key.

Since objects are associative/hash arrays ie defined and created with keys and values how is the String constructor returning an object with a value without key?

Answer 1

It doesn't.

You're just misinterpreting the console's visualisation of a string object and assuming it is expressing it in the form of object literal syntax. If it would, you would see:

 { 0: "h", 1: "e", 2: "l", 3: "l", 4: "o", length: 5, __proto__: String }

But thats certainly quite unreadable, so they probably changed the way of visualizing to make it easier to read.