I was working on a Timer code and was facing issue with it and posted a question regarding it. After discussion, thanks to @James, I found it was JSFiddle issue.
JSFiddle Link: http://jsfiddle.net/RajeshDixit/0gvfc5yy/4/
CodePen Link: http://codepen.io/rajesh_dixit/pen/RWBowQ
When you run it on JSFiddle, you will get following error
Uncaught ReferenceError: startTimer is not defined
But works fine on CodePen and in snippet below.
function timer() {
    var time = {
        sec: 00,
        min: 00,
        hr: 00
    }
    var max = 59;
    var interval = null;
    function update(str) {
        time[str]++;
        time[str] = time[str] % 60;
        if (time[str] == 0) {
            str == "sec" ? update("min") : update("hr");
        }
        print(str);
    }
    function print(str) {
        var _time = time[str].toString().length == 1 ? "0" + time[str] : time[str];
        document.getElementById("lbl" + str).innerHTML = _time;
    }
    function initInterval() {
        interval = setInterval(function () {
            update("sec");
        }, 1000);
    }
    function stopTimer() {
        clearInterval(interval);
    }
    return {
        'init': initInterval,
            'stop': stopTimer
    }
};
var time = new timer();
function startTimer() {
    time.init();
}
function endTimer() {
    time.stop();
}
<div> <span id="lblhr">00</span>
: <span id="lblmin">00</span>
: <span id="lblsec">00</span>
</div>
<button onclick="startTimer()">Start</button>
<button onclick="endTimer()">Stop</button>