parallel.js

var count = 3;

function next() {
  count--;
  if (count === 0) {
    // continue
  }
}

doAjax("do", next);
doMoreAjax("it", next);
MOARAJAX("parallel", next);

using-after.js

var next = after(3, function _next() {
  // continue
}); 

doAjax("do", next);
doMoreAjax("it", next);
MOARAJAX("parallel", next);