Andrei Zhamoida - 1 year ago 51

Javascript Question

Here's a trick question i can't figure out. As I read from MDN we cannot create instance from

`Math`

`new Math()`

`Math is not a constructor`

`Math.constructor`

`Object`

`Math.constructor()`

`Math.constructor = Function.constructor`

Now I had some suppositions in my mind:

- constructor contains a hidden property and browser engine refuses invoke it.
- constructor interpreted into special c++ object in browser engine which has index in "TypeError:not a constructor" collection.

Could someone answer me thoroughly why constructor exists but I cannot create an instance?

Thanks in advance.

Answer Source

To quote myself, the answer is

because the spec says so

and the spec says

The Math ObjectThe Math object is a single object that has some named properties, some of which are functions.

The value of the

`[[Prototype]]`

internal property of the Math object is the standard built-in Object prototype object (15.2.4). The value of the`[[Class]]`

internal property of the Math object is "Math".

The Math object does not have a`[[Construct]]`

internal property; it is not possible to use the Math object as a constructor with the new operator.The Math object does not have a

`[[Call]]`

internal property; it is not possible to invoke the Math object as a function.

Every object in javascript has a constructor, and `Math`

is an object, hence it has a constructor, that doesn't mean you can create new instances of it, it's the same as

```
var Math = {
random : true,
max : false
}
new Math(); // epic fail, not a constructor (function)
```