How to call a callback from a conditional async function

Question

How to call a callback from a conditional async function

Given this code:

var something = function(callback) {

  if(condition) {
     Mongoose.findOne(id, function(err, doc) {
       if(doc) {
         callback(doc);
       } else {
         callback();
       }
    });
  } else {
    callback();
  }
}

How would I rewrite it in a cleaner way so that 'callback' is just called in one place. I assume I can wrap this entire thing somehow and do that - I've seen it but cannot get it quite right.

javascript
node.js

Answer 1

Since you said there are complex steps to call the callback, try the below

var something = function(callback) {
    var callCallback = function(doc){
        //do all other things you want to do to call the callback
        callback(doc);
    };

    if(condition) {
        Mongoose.findOne(id, function(err, doc) {
            if(doc) {
                callCallback(doc);
            } else {
                callCallback();
            }
        });
    } else {
        callCallback();
    }
}

Answer 2

var something = function (callback) {
  var f = function (e, d) { callback(d) };

  if (condition) {
     Mongoose.findOne(id, f);
  } else {
    f();
  }
}

my reasoning is that if d is false then we still can pass it on to callback and it will be the same almost as passing no arguments at all.