Synchronizing Multiple AJAX Calls In Window.onload() Event

function addLoadEvent(func) {
var oldonload = window.onload;
if (typeof window.onload == 'function') {
window.onload = function() {
oldonload();
func();
}
} else {
window.onload = func;
}}

addLoadEvent(myFunction1);
addLoadEvent(myFunction2);
addLoadEvent(myFunction3);
...etc...

My problem is that some of these myFunction#s include AJAX calls but
the calls depend on each other in such a way that myFunction2 will not
work unless myFunction1 has completed. So what is the "nicest" way to
make sure of this? I've considered putting a hidden element in the
HTML and then changing it at the end of each function call and have
the onchange event trigger the next function call. But this seems very
hacky and overcomplicated - surely there must be a simpler and better
way....?