Queue processing with Q promises

gistfile1.js

function processSequentially()
{
    console.log("start queue");
    var result = Q.defer();
    var done;
    [
        ["1", 2],
        ["2", 4],
        ["3", 3],
        ["4", 9],
        ["5", 2]
    ].forEach(function(event)
    {
        done = Q.when(done, function()
        {
            var work = Q.defer();
	        console.log("start task: " + event[0]);
	        setTimeout(function()  // simulate async call
	        {
                console.log("end task: " + event[0]);
	            work.resolve();
	        }, 100 * event[1]);
            return work.promise;
        });
    });
    Q.when(done, function()
    {
        console.log("end queue");
        result.resolve();
    });
    return result.promise;
}


function processParallel()
{
    console.log("start queue");
    var result = Q.defer();
    var done;
    [
        ["1", 2],
        ["2", 4],
        ["3", 3],
        ["4", 9],
        ["5", 2]
    ].forEach(function(event)
    {
        var work = Q.defer();
        console.log("start task: " + event[0]);
        done = Q.when(done, function()
        {
            return work.promise;
        });
        setTimeout(function()  // simulate async call
        {
            console.log("end task: " + event[0]);
            work.resolve();
        }, 100 * event[1]);
    });
    Q.when(done, function()
    {
        console.log("end queue");
        result.resolve();
    });
    return result.promise;
}