Why doesn't JavaScript allow assigning the property "name" on a Function?

Question

See below for what happened in Firefox and Chrome's console:

> var f = function() {}
undefined
> f.name = 'f'
"f"
> f.name
""
> f.id = 1
1
> f.id
1

Why f.name = 'f' is a no-op?

Answer 1

Probably depends on the implementation.

In some implementations, the name property of a function object is used as the function's name if it has one. This is likely read-only in these cases.

This is a non-standard feature.

for example:

var foo = function bar() {};

alert(foo.name); // will give "bar" in some cases. 

---

In Firefox and Chrome, if I try to modify it, it won't change...

var foo = function bar() {};

foo.name = "baz";
alert(foo.name); // still "bar" in Firefox and Chrome

---

• MDN docs for the name property.

Here are some key points from the docs...

"Non-standard"

"The name property returns the name of a function, or an empty string for anonymous functions"

"You cannot change the name of a function, this property is read-only"