嵌套的递延Q Promises解决方案可以简化吗？

Question

I have combined some typical (anti-)pattern I have come along, looking at javascript using the Q library :

How much of this can be simplified? (or is pointless) Especially:

• A: What is the value in deferred.resolve(... over returning a value and thus resolving right away? Only the fact, that code that further code get's executed, ie. doSomeMore() ?
• if so, for A2 this is pointless in this code?
• B: What is the value in deferred.reject over throw throw new Error('')

• C: The try-catch also irritates me. Only to ensure doSomeMore() ?

  function foo(u) {

   var deferred = Q.defer(); bar(u).then( function (v) { if (v==42) { deferred.resolve( Q(null) ); // A } else { try { var controller = new Controller(); deferred.resolve( controller ); // A2 } catch (error) { deferred.reject(error); // B,C } doSomeMore(); } return deferred.promise; }); 

  }

Answer 1

Yes, the purpose of this code seems to be ensuring that doSomeMore() is executed regardless what happened when the Controller was constructed. You could get that more easily though:

function foo(u) {
    return bar(u).then(function (v) {
        if (v == 42) {
            return null;
        } else {
            try {
                return new Controller();
            } finally {
                doSomeMore();
            }
        }
    });
}

Answer 2

Something like this maybe?

return bar(u).then(function (v) {      
  if (v==42) 
    return null;  
  return new Controller();  
}).finally(function() { doSomeMore(); });