function's chaining

gistfile1.js

// (start) -> Any jobs... -> "OK 1" -> Any jobs... -> "OK 3" -> Any jobs... -> "OK 3"
Promise(function(resolve) {
  console.log('OK 1');
  setTimeout(resolve, 1000);
}).then(function() {
  Promise(function(resolve) {
    console.log('OK 2');
    setTimeout(resolve, 1000);
  }).then(function() {
    console.log('OK 3');
  });
});