Prongo

bad.js

var mongodb = require('mongodb');
var express = require('express');

var app = express.createServer();
var db = new mongodb.Db('mysite',
                        new mongodb.Server('localhost', 27027, {}),
                        {native_parser: true});

app.get('/', function(req, res) {
    // Open the connection.
    db.open(function(err, db) {
        // Get one collection.
        db.collection('users', function(err, usersColl) {
            // Search the first collection.
            usersColl.find({}, {'limit': 3}, function(err, usersCursor) {
                // Convert the result into an array.
                usersCursor.toArray(function(err, users) {
                    // Get the second collection.
                    db.collection('articles', function(err, artColl) {
                        // Search the second collection.
                        artColl.find({}, {'limit': 3}, function(err, artCursor) {
                            // Convert the result into an array.
                            artCursor.toArray(function(err, articles) {
                                // Now we have two arrays, users and articles, in scope.
                                // Render the home page.
                                res.render('home.ejs', {'users': users, 'articles': articles});
                            });
                        });
                    });
                // OH GOD WHY
                });
            });
        });
    // CLOSE EVERYTHING
    });
});

better.js

var mongodb = require('mongodb');
var express = require('express');
var prongo = require('./prongo.js');
var Deferred = require('Deferred');

var app = express.createServer();
var db = new mongodb.Db('mysite',
                        new mongodb.Server('localhost', 27027, {}),
                        {native_parser: true});


function home(req, res) {
    var uDef = prongo.getArray(db, 'users', {}, {'limit': 3});
    var aDef = prongo.getArray(db, 'articles', {}, {'limit': 4});
    var lookup = Deferred.when(uDef, aDef);
    lookup.done(function(users, articles)) {
        res.render('home.ejs', {'users': users, 'articles': articles});
    }).fail(function(err) {
        res.render('error.ejs', {'error': err})
    });
}

app.get('/', home);

django-example.py

def home(request):
    foos = Foo.objects.all().orderby('-created')[0:5]
    bars = Bar.objects.all().orderby('-created')[0:5]
    return render(request, 'home.html', {'foos': foos, 'bars': bars})

mixed.php

<h1><?= mysql_query($my, "SELECT title FROM posts WHERE..."); ?></h1>

ohgod.js

                            });
                        });
                    });
                // OH GOD WHY
                });
            });
        });
    // CLOSE EVERYTHING
    });
});

prongo.js

var Deferred = require('Deferred');

exports.getArray = function getArray(db, coll, search, options) {
    var def = Deferred();
    db.open(function(err, db) {
        if (err) def.reject(err);
        db.collection(coll, function(err, collection) {
            if (err) def.reject(err);
            collection.find(search, options, function(err, cursor) {
                if (err) def.reject(err);
                cursor.toArray(function(err, arr) {
                    if (err) def.reject(err);
                    def.resolve(arr);
                });
            });
        });
    });
    return def.promise();
}

sobad.js

app.get('/', function(req, res) {
    // Open the connection.
    db.open(function(err, db) {
        // Get one collection.
        db.collection('users', function(err, usersColl) {
            // Search the first collection.
            usersColl.find({}, {'limit': 3}, function(err, usersCursor) {
                // Convert the result into an array.
                usersCursor.toArray(function(err, users) {
                    // Get the second collection.
                    db.collection('articles', function(err, artColl) {
                        // Search the second collection.
                        artColl.find({}, {'limit': 3}, function(err, artCursor) {
                            // Convert the result into an array.
                            artCursor.toArray(function(err, articles) {
                                // Now we have two arrays, users and articles, in scope.
                                // Render the home page.
                                res.render('home.ejs', {'users': users, 'articles': articles});