javascript - Function declaration in CoffeeScript

Question

I notice that in CoffeeScript, if I define a function using:

a = (c) -> c=1

I can only get the function expression:

var a;
a = function(c) {
    return c = 1;
};

But, personally I often use function declaration,for example:

function a(c) {
    return c = 1;
}

I do use the first form, but I'm wondering if there is a way in CoffeeScript generating a function declaration. If there is no such way, I would like to know why CoffeeScript avoid doing this. I don't think JSLint would holler an error for declaration, as long as the function is declared at the top of the scope.

Answer 1

CoffeeScript uses function declarations (aka "named functions") in just one place: class definitions. For instance,

class Foo

compiles to

var Foo;
Foo = (function() {
  function Foo() {}
  return Foo;
})();

The reason CoffeeScript doesn't use function declarations elsewhere, according to the FAQ:

Blame Microsoft for this one. Originally every function that could have a sensible name retrieved for it was given one, but IE versions 8 and down have scoping issues where the named function is treated as both a declaration and an expression. See this for more information.

In short: Using function declarations carelessly can lead to inconsistencies between IE (pre-9) and other JS environments, so CoffeeScript eschews them.