Accessing Closures In SetTimeout?

When writing JS, I try to encapsulate my code somehow. For instance, in the example below, I have a function ('testFunc') that's encapsulated within jQuery's document.ready callback function :

Code:
$(function(){
var testFunc = function(x){
x++;[code]...

If I then start using JS's base timer functions like settimeout, I've always been unsure of how to access the 'testFunc' function. As I understand it, even if the timer functions are called inside the same function, as in...

Code:
$(function(){
var testFunc = function(x){
x++;
return x;
}

var timer = setTimeout("testFunc", 100);
});

... they will lose the scope of the jQuery callback - instead the timer functions will only be able to access objects in the global scope.