Edit in JSFiddle

var log = function(content){
    $('<p/>').html(content).appendTo('#log');
}

function doTask(i, next){
    setTimeout(function(){
        log("Step " + ++i + " finished.");
        next();
    }, Math.random()*1000);
}
    
$(function(){
    doTask(0, function(){
        doTask(1, function(){
            doTask(2, function(){
                doTask(3, function(){
                    doTask(4, function(){
                        log("All steps done.");
                    });
                });
            });
        });
    });
});

<div id="log"></id>