nodejs-async-blocks-example-async

async.js

async.series({
    somedata: function(callback){
        // query the database to get "somedata" and pass the result to callback
    },
    someextradata: function(callback){
       // query the database to get the "someextradata" and pass the result to callback
    },
},
function(err, results) {
    // results is now equal to: {somedata: yourData, someextradata: yourExtraData}
});

callback-hell.js

function getData(id, callback) {

  db.blogs.find(function(error, result) {

    var someData = result;

    db.somethingElse.find(function(err, result) {

      var someExtraData = result;

      var results = {

         someData: someData,

         someExtraData: someExtraData

       }

      callback(error, results)

    })

  })

}

jquery.js

$.get("http://example.com/someExtraData", function(data) {

  // Do something with your data like:

  $("ul").append("<li>" + data.title +"</li>");

})

json.js

app.get("/someExtraData", function(req, res) {

  var someExtraData = { // This will come from the database }

  res.json(someExtraData)

})