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by bphogan 5222 days ago
All the examples, github repos, books, and tutorials I'm seeing with my dive into node say exactly the opposite - the code becomes a mess of callbacks. It looks like enormous work goes into avoiding callbacks, similar to the amount of work that went into Rails in 2005 so that server-side folks could avoid writing JavaScript.

I'd love to see this framework you wrote. Is it open-source? or is it something you're unable to share?

1 comments

You have to think about async code differently than you think about synchronous code. In PHP you might write:

  $data = getData();
And people want to substitute the return for a callback in js.

  getData(function(data) {
    // Do something with data.
  });
That indeed does lead to callback mess. But when you are coding in js you rarely should use anonymous functions. I mostly just use them when I might want to perform recursion. Going back to my example, I would write the operation as an object like so:

  var SomeObject = {
    start: function() {
      getData(dataGot);
    },

    dataGot: function(data) {
      
    }
  };
JavaScript is an object-oriented languages; use objects! They make async painless.
Wrapping things in objects doesn't seem to help me.

I'd still end up with this, thanks to callbacks.

    app.get('/documents', function(req, res) {
      Document.find().all(function(documents) {
        // 'documents' will contain all of the documents returned by the query
        res.send(documents.map(function(d) {
          // Return a useful representation of the object that res.send() can send as JSON
          return d.__doc;
        }));
      });
    });
Seems to me that what's missing is something that lets me write it in a more simple way. What I have here looks like an absolute nightmare of coupling. So if you have some suggestions you could point me to that show a little more detail, I'd be really grateful.
I would create a DocumentRequest object that takes your req and res, then break apart your callbacks to separate functions on the DocumentRequest prototype. Then you would simply consume it with:

  app.get('/documents', new DocumentRequest);
Thanks for this. Been thinking about this. Could you recommend a book on patterns like these?
> JavaScript is an object-oriented languages; use objects! They make async painless.

In the example above, you're unable to use ''this'' in the ''dataGot'' function (when invoked as a callback).

Object orientedness is very easy to get wrong in JavaScript, if you're coming from C++/Java/Python background.

Right, I excluded the bind for the sake of simplicity.

I also forgot that it's this.dataGot. dataGot doesn't exist in that context :)