Q deferred promises chain

sample.js

Q = require('q')

var A = function() {

    var d = Q.defer()
    
    var result = 'A is done'

    console.log(result)
    d.resolve(result);
    
    return d.promise
}

var B = function() {

    var d = Q.defer()

    var result = 'B is done'

    setTimeout(function() {
        console.log(result)
        d.resolve(result);
    }, 2000)

    return d.promise
}

var C = function() {

    var d = Q.defer()

    var result = 'C is done'
    console.log(result)
    d.resolve(result);

    return d.promise
}

var D = function() {

    var d = Q.defer()

    var result = 'D is done'
    console.log(result)
    d.resolve(result);

    return d.promise
}

A()
.then(function(result) { 
    return B();
})
.then(C)
.then(D)