Difference between Static function declaration and the normal function declaration in Javascript?

Question

There are many ways one can declare a function in javascript. One of the ways is declaring a class and a static function inside is as showed below.

class className {
 static fucntionName() {
 }
}

another way of is declaring is through the tradition javascript style as showed below.

function functionName() {
}

I would like to know the advantages/disadvantages of using either of the cases. Is there any specific use cases for the static methods, why declare a class(we know that in javascript there is no need to instantiate the class in order to access the static function). Why not just use the traditional way (the second case in the above example) of function declaration in all/any use case?

I would like to understand this is in detail.

Answer 1

I would like to know the advantages/disadvantages of using either of the cases.

apples and oranges. A class doesn't have to be exported and a module doesn't have to be a class. They are not the same thing, although the exported module can be a class.

Is there any specific use cases for the static methods

When you want a class to provide some functionality, but this aint' something that is specific to a single instance of that class. Like var c = Point.interpolate(a, b, .5);
The static interpolate function doesn't belong to any of the points it's operating on. It's more appropriate to define this function static on the class that provides this functionality (interpolating points).

we know that in javascript there is no need to instantiate the class in order to access the static function

That's the very definition of a static function that you don't have to instantiate the class to call it. That's not something JS specific.

Why not just use the traditional way (the second case in the above example) of function declaration in all/any use case

Because as I started, a class and a module ain't necessarily the same thing. And it is nicer/cleaner to write

class Foo{
    ...
    static fn(){...}
}

than

class Foo {
    ...
}

Foo.fn = function(){...};

Although in the end, both is just little more than

function Foo(){...}
Foo.fn = function(){};
// + Foo.prototype stuff

But the class syntax is cleaner. Simpler to read and to understand, even if you're just scanning over this piece of code.