Can a JavaScript object have a prototype chain, but also be a function?

Question

function a () {
    return \"foo\";
}

a.b = function () {
    return \"bar\";
}

function c () { };
c.prototype = a;

var d = new c();
d.b(); // returns \"bar\"
d()         


        

Answer 1

Does it have to actually be a prototype chain? You can use a mixin pattern to make a function have all of the properties of a instead. You can even wrap it in a nice "new" syntax to fake it if you really want.

function a () {
    return "foo";
}

a.b = function () {
    return "bar";
}

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

    //mixin all properties on a
    for(var prop in a){
        f[prop] = a[prop];
    }

    return f; //just returns the function instead of "this"
};

var d = new c(); //doesn't need the new keyword, but just for fun it still works

alert(d()); //show "foo"

alert(d.b()); //shows "bar"

You can add properties to d without affecting a. The only difference between this and what you want is that changes to a will not affect existing "instances" of c.