Function which returns function

Question

Let's say there are two ways to define a function:

First way:

Bar.prototype.foo = function ()
{
  // do something
}

Second way:

Bar.prototype.foo = function ()
{
    return function () {
        // do something
    }
}

For sure the second way is useful in case of closure.

There are other case where the second way is preferable to the fist one?

Answer 1

I have had a project in where I dynamically built validator functions for certain input types in a way similar to the closure case.

So returning different function based on the input parameters might be a valid usecase for the later way to define a function.

Answer 2

You can use it do y combinator style work, see this answer: https://stackoverflow.com/a/94056/426894