gistfile1.js

alert(typeof(f)); // --> function
function f() {}

gistfile2.js

alert(typeof(f)); // --> undefined
var f = function () {};

gistfile3.js

var f = function () {
    return typeof(f);  
}

var g = f; 
f = 42;

alert(g()); // --> number

gistfile4.js

var f = function f() {
    return typeof(f);  
}

var g = f; 
f = 42;

alert(g()); // --> function