A Simple Timer

<script type="text/javascript">
<!--
active=0
restart=0
time=""

function initTimer(){
if(active==1){return}
active=1
restart=1
i=0
num=document.f1.t1.value
document.f1.b2.value=" Pause "
countdown()
}

function rstart(){
if(restart==1){return}
active=1
restart=1
countdown()
}

function countdown(){
document.getElementById("display").innerHTML=num
if (num>2){
document.getElementById("display").style.color="black"
}
else{
document.getElementById("display").style.color="red"
}
if (num== 0){

// YOUR_FUNCTION (optional)

num=document.f1.t1.value // reset display to show 5
document.getElementById("display").innerHTML=num
display.style.color="black"
cease()
return
}
else{
num--
time=setTimeout("countdown()", 1000);
}
}

function cease(){
clearTimeout(time)
active=0
restart=0
}

var i=0
function dualButt(){
i++
if (i==1){
cease()
document.f1.b2.value="Restart"
}
else
if (i==2){
rstart()
document.f1.b2.value=" Pause "
i=0
}
}

// add onload="initTimer()" to the opening body tag

//-->
</script>

<form name=f1>
<div id=display style="position:absolute; top:90; left:225;width:200;font-size:250px;text-align:center"></div>

<div style="position:absolute; top:345; left:225;width:200; height:30;text-align:center">
<input type=text name=t1 value=10 size=4>
<input type=button name=b1 value="Start" onclick="initTimer();this.blur"> 
<input type=button name=b2 value=" Pause " onclick="dualButt();this.blur">
</div>
</form>