conditionally executing a callback

Question

What's the best way to solve the following control flow niggle:

1. I only want to call getSomeOtherData if someData is equal to some value / passes some conditional test

2. In both cases I always want to call getMoreData

http.createServer(function (req, res) {
    getSomeData(client, function(someData) {
        // Only call getSomeOtherData if someData passes some conditional test
        getSomeOtherData(client, function(someOtherData) {
           // Always call getMoreData
           getMoreData(client, function(moreData) {
             res.end();
           });
       });
   });
});           

Answer 1

No great solution to this; the best I've found is to make a local function that takes care of the remaining common work like this:

http.createServer(function (req, res) {
  getSomeData(client, function(someData) {
    function getMoreAndEnd() {
       getMoreData(client, function(moreData) {
         res.end();
       });
    }

    if (someData) {  
      getSomeOtherData(client, function(someOtherData) {
        getMoreAndEnd();
      });
    } else {
      getMoreAndEnd();
    }
  });
});