How to create a count up timer in a text input?

Question

Below I have a javascript count down timer which works fine:

    <h1><span id='countdown'><?php echo $dbSessionDuration; ?></span></h1>

...

  $(document).ready(function() {
    var time = <?php echo json_encode($dbSessionDuration); ?>,
      parts = time.split(':'),
      hours = +parts[0],
      minutes = +parts[1],
      seconds = +parts[2],
      span = $('#countdown');


    function correctNum(num) {
      return (num<10)? ("0"+num):num;
    }

    var timer = setInterval(function(){
        seconds--;
        if(seconds == -1) {
            seconds = 59;
            minutes--;

            if(minutes == -1) {
                minutes = 59;
                hours--;

                if(hours==-1) {
                  alert("timer finished");
                  clearInterval(timer);
                  return;
                }
            }
        }
        span.text(correctNum(hours) + ":" + correctNum(minutes) + ":" + correctNum(seconds));
    }, 1000);

});

Now what I thought of doing is use the example above and manipulate it to now do the opposite and create a count up timer starting with 00:00:00 (hours, mins, secs).

But issue is that it is not working. Nothing is happening. I don't know if I need an hours in the function below because as its a countup, the hours could go up to as many hours as it wants. But my question is how can the count up timer be fixed so that it is fully working?

<p><input type='text' class='responseTime' name='responsetime' value='00:00:00' /></p>

...

$(document).ready(function() {
var response = "00:00:00",
      parts = time.split(':'),
      hours = +parts[0],
      minutes = +parts[1],
      seconds = +parts[2],
      input = $('.responseTime');


    function correctResponse(responsenum) {
      return (responsenum<10)? ("0"+responsenum):responsenum;
    }

    var responsetimer = setInterval(function(){
        seconds--;
        if(seconds == +59) {
            seconds = 00;
            minutes--;

            if(minutes == +59) {
                minutes = 00;
                hours--;

                  return;

            }
        }
        input.text(correctResponse(hours) + ":" + correctResponse(minutes) + ":" + correctResponse(seconds));
    }, 1000);


  });

UPDATE:

Also as a side note I realised that the countdown timer I believe is counting down every 2 second for every second. How can this be sorted for the count down timer and included in the count up timer?

The code below I have changed to include increment ++ and to include .val rather than .text but what is happening is that it starts with 00:00:00 and then it just drops down to 00:59:60 and then just stops:

var response = "00:00:00",
          parts = time.split(':'),
          hours = +parts[0],
          minutes = +parts[1],
          seconds = +parts[2],
          input = $('.responseTime');


        function correctResponse(responsenum) {
          return (responsenum<10)? ("0"+responsenum):responsenum;
        }

        var responsetimer = setInterval(function(){
            seconds++;
            if(seconds == +59) {
                seconds = 00;
                minutes++;

                if(minutes == +59) {
                    minutes = 00;
                    hours++;

                      return;

                }
            }
            input.val(correctResponse(hours) + ":" + correctResponse(minutes) + ":" + correctResponse(seconds));
        }, 1000);


      }); 

Answer 1

You could easily modify the current countdown timer like here: http://jsfiddle.net/Sergiu/CDpeJ/3

var timer = setInterval(function(){
    seconds++;
    if(seconds == 60) {
        seconds = 00;
        minutes++;

        if(minutes == 60) {
            minutes = 00;
            hours++;
        }
    }
    var newTime = hours + ":" + minutes + ":" + seconds;
    if(!newTime.match(/^(20|21|22|23|[01]\d|\d)(([:.][0-5]\d){1,2})$/)) newTime = "finished";
    $('#timeInput').val(newTime);
}, 1000);

Answer 2

In jQuery, use the val('value') function to change/set the value of an input field.

Change input.text(...) to input.val(...)

Also:

1. After incrementing seconds use seconds = seconds % 60; to bring them back to 0.
2. Also, consider using data-attributes for passing values to javascript.