Lenguaje HTML/Comportamiento

<body onload="startclock()">
<script language="JavaScript">
<!--
var timerID = null
var timerRunning = false
function stopclock(){
    if(timerRunning)
        clearTimeout(timerID)
    timerRunning = false
}
function startclock(){
     // Make sure the clock is stopped
    stopclock()
    showtime()
}
function showtime(){
    var now = new Date()
    var hours = now.getHours()
    var minutes = now.getMinutes()
    var seconds = now.getSeconds()
    var timeValue = "" + ((hours > 12) ? hours - 12 : hours)
    timeValue  += ((minutes < 10) ? ":0" : ":") + minutes
    timeValue  += ((seconds < 10) ? ":0" : ":") + seconds
    timeValue  += (hours >= 12) ? "  PM" : "  AM"
    document.clock.face.value = timeValue
    timerID = setTimeout("showtime()",1000)
    timerRunning = true
}

function reloj(){
	if(timerRunning)
        stopclock()
	else
		startclock()
}
//-->
</script>

<form name="clock" onsubmit="0">
    <p><input type="button" name="face" value="hh:mm:ss am"
    onclick="reloj()"> </p>
</form>
</body>