var timerInit = function(cb, time, howOften) {

  // time passed in is seconds, we convert to ms

  var convertedTime = time * 1000;

  var convetedDuration = howOften * 1000;

  var args = arguments;

  var funcs = [];

  for (var i = convertedTime; i > 0; i -= convetedDuration) {

    (function(z) {

      // create our return functions, within a private scope to preserve the loop value

      // with ES6 we can use let i = convertedTime

      funcs.push(setTimeout.bind(this, cb.bind(this, args), z));

    })(i);

  }

  // return a function that gets called on load, or whatever our event is

  return function() {

    //execute all our functions with their corresponsing timeouts

    funcs.forEach(function(f) {

      f();

    });

  };

};

​

// our doer function has no knowledge that its being looped or that it has a timeout

var doer = function() {

  var el = document.querySelector('#time');

  var previousValue = Number(el.innerHTML);

  document.querySelector('#time').innerHTML = previousValue - 1;

};

​

​

// call the initial timer function, with the cb, how many iterations we want (30 seconds), and what the duration between iterations is (1 second)

window.onload = timerInit(doer, 30, 1);

​

​