[tonyle]

I'm not sure when promises came to the javascript, but it seems weird that people would settle with callback hell for so long without even attempting to refactoring it.

I mean if I didn't have the option of using promises, I would have probably written something like this.

function handler(callback){

  var state={};

  function logic(step,err,data){  
    if(!step){
      connectToDb("somedatabase",logic.bind(state,1))
    }
    
    if(step==1){
      if(err) callback("error1")
      state.dbInstance=data
      state.dbInstance.query("someQuery",logic.bind(state,2))
    }
    
    if(step==2){
      if(err) callback("error2")
      csvExporter(data,logic.bind(state,3))
    }

    if(step==3){
      if(err) callback("error3")
      callback(data)
    }
  }
  logic()
}

[sleazebreeze]

That looks like a very similar pattern that I've seen commonly used in Go. It makes for very clear code and explicit error handling. I kind of like it for the clarity, even if it isn't "elegant" or concise.

[xyzzy123]

Did you mean return callback("error1") etc? Forgetting the return is a classic bug when you're in callback hell...

[angersock]

Yeeeeep.

I think the example and your reply neatly illustrate the problem.