一线式将原型方法转换为JavaScript中的函数

Question

The String object in Javascript has a method called toLowerCase . The problem with that method is that it requires that you already have a String object.

What if I wanted to turn that prototype method into a function that could be called on a String?

I know that I can do this:

var f = function (str) { return str.toLowerCase(); }
f("HI") // = "hi"

I want to avoid using the function keyword.

I thought that, since I can do this...

String.prototype.toLowerCase.call("HI") // = "hi"

...that I could then do this:

var f = String.prototype.toLowerCase.call
f("HI")

But this results in an error:

Uncaught TypeError: f is not a function

Same goes for apply and bind .

I want the resulting function to be callable using f("HI") , so using call and apply aren't allowed.

Is there way to accomplish this without resorting to using function ?

For those of you who will inevitably wonder why I won't use the function keyword, it's just curiosity to help me understand JavaScript better. I'm not trying to be fancy, or efficient, or anything. I'm not trying to optimize prematurely, etc., so please refrain from Knuth quotes.

Answer 1

Got it. Quite a mental puzzle you put together, and I wasn't sure there was any way to have the first argument be accepted how we want it.

var pointlessFunctionBindingForJavascriptHackers =
   Function.prototype.call.bind(String.prototype.toLowerCase)

Answer 2

Is it cheating to precreate an demethodize function?

function demethodize(meth) {
    return function () {
        return Function.prototype.call.apply(meth, arguments);
    }
}

var f = demethodize(String.prototype.toLowerCase);

At least, I hope this may satisfy your "help me understand JavaScript better" requirement. :-)