Promises doodle

doodle.js

function retProm() {
 var def = when.defer();

 return def.resolve();
}

console.log('one');
retProm().then(function(){console.log('two'));
console.log('three');

// this will print:
//
// one
// three
// two

No, this could print Z, Y, X. There is no requirement that X come before Y. The spec is still following as long as Y comes after Z.

Let me explain further the difference between our two examples. In yours, when you call def.resolve, then has not yet returned. So the implementation must insert an extra tick before calling onFulfilled, to ensure that then returns first.

In my example, when I call def.resolve, then has already returned, since an async operation has already happened. So the implementation does not have to insert an extra tick before calling onFulfilled, since then has already returned.