JavaScript Promise then() ordering

Question

I\'m still learning JavaScript Promises, and I came across a behavior I don\'t understand.

Answer 1

What does r() do?

The ordering is indeterminate because you're thenning on the same promise -> this specifically refers to the second and third chain.

If you were doing the following, then order can be guaranteed:

var p = Promise.resolve().then(function() {
    w(0);
}).then(function() {
    w(1);
});

// Key difference, continuing the promise chain "correctly".
p = p.then(function() {
    w(2);
    return new Promise(function(r) {
        w(3);
        r();
    }).then(function() {
        w(4);
    });
}).then(function() {
  w(5);
});

p.then(function() {
  w(6);
});