​x
 
<!DOCTYPE html>
<html>
​
<head>
<script>
    //Counter increments every 1s.
    var counter = setInterval(function(){startCount()},1000);
    //Counter starts from 1.
    var initVal = 1;
    function startCount(){
        //Counter value is displayed in text box.
        var count = document.getElementById('txtBox');
        count.value = initVal++;
    }           
</script>
</head>
​
<body>
    <input type="text" id="txtBox">
    <br/><br/>
    <button onclick="startCount()">Start Counter</button>
    <button onclick = "clearInterval(counter)">Stop Counter</button>
    <p>Buttons to start and stop counter. clearInterval() stops counter.</p>
</body>
​
</html>