1var btn = document.getElementById("btn");
2
3btn.addEventListener("click", handler, false);
4
5function handler(e) {
6  console.log("handler triggered");
7  doSomething();
8  console.log("handler done");
9}
10
11function doSomething() {
12  doThis();
13  doThat();
14  doTheOther();
15}
16
17function doThis() {
18  console.log("doThis - start & end");
19}
20function doThat() {
21  console.log("doThat - start");
22  // do something that takes a while
23  var stop = Date.now() + 1000;
24  while (Date.now() < stop) {
25    // wait
26  }
27  console.log("doThat - end");
28}
29function doTheOther() {
30  console.log("doThat - start & end");
31}