callback-soup.js

var allBlogs = function(cb){
  Blog.find({}, function(err, docs){
    if(err){
      cb(err, null);
    }
    else{
      cb(null, docs);
    }
  });
};
 
// give the create functions enough time to run
// before returning list of all blogs
setTimeout(function(){
 allBlogs(function(err, docs){
  console.log(docs);
 }); 
}, 3000);