The following is nasty, but serves to demonstrate how you can treat functions like any other kind of object.
var foo = function () { alert('default function'); }
function pickAFunction(a_or_b) {
var funcs = {
a: function () {
alert('a');
},
b: function () {
alert('b');
}
};
foo = funcs[a_or_b];
}
foo();
pickAFunction('a');
foo();
pickAFunction('b');
foo();