Tasker - Task synchronizer - kind of a 'purposed' Promise

Tasker example with 5 taks 0..4, where task 1 and 3 fail (emulated) twice and once and succeed in 3rd and 2nd try, respectively.

// Setup of 5 task: t0..t4

var t0 = function(done) { // task0
  console.log("t0 started");
  setTimeout(function(){
    done(true);
  },5000);
};

var t1 = function(done,trie) {
  console.log("t1 started");
  setTimeout(function(){
    var ok = trie >= 3; // emulating failure on 1st & 2nd try
    console.log("t1 " + trie + " ok: " + ok);
    done(ok,3); // allow 3 tries
  },2000);
};

var t2 = function(done) {
  console.log("t2 started");
  setTimeout(function(){
    done(true);
  },15000);
};
var t3 = function(done,trie) {
  console.log("t3 started");
  var ok = trie >= 2;
  console.log("t1 " + trie + " ok: " + ok);
  setTimeout(function(){
    done(ok,2);
  },2500);
};
var t4 = function(done) {
  console.log("t4 started");
  setTimeout(function(){
    done(true);
  },12500);
};

// define ok function - application
var ok = function(oks,sts,tries,tasks) {
  console.log("All " + oks + 
    " tasks successfully executed.");
};

// define err function
var err = function(oks,sts,tries,tasks) {
    console.log("Only " + oks + " tasks of " + 
      sts.length + " successfully executed.");
};


// Execute the tasks 
new Tasker([t0,t1,t2,t3,t4],ok,err,true);

The console output reads as follows:

 1v71 Copyright 2014 G.Williams
>echo(0);
Task 0 kickoff 1
Task 1 kickoff 1
Task 2 kickoff 1
Task 3 kickoff 1
Task 4 kickoff 1
=undefined
t0 started
t1 started
t2 started
t3 started
t1 1 ok: false
t4 started
t1 1 ok: false
Task 1 try 1 ok: false
Task 1 kickoff 2
t1 started
Task 3 try 1 ok: false
Task 3 kickoff 2
t3 started
t1 2 ok: true
t1 2 ok: false
Task 1 try 2 ok: false
Task 1 kickoff 3
t1 started
Task 0 try 1 ok: true
Task 3 try 2 ok: true
t1 3 ok: true
Task 1 try 3 ok: true
Task 4 try 1 ok: true
Task 2 try 1 ok: true
All 5 tasks successfully executed.
>