为什么我这个程序写出来并不会计数？
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>计时器</title>
<script type="text/javascript">
var num=0;
var i;
function startCount(){
document.getElementById('count').value=num;
num=num+1;
i=setTimeout("startCount()",1000);
}
function stopCount(){
clearTimeout(i);
}
function overs(
setTimeout("startCount()",1000); ){
var d=document.getElementById('count');
d.style.backgroundColor="#000";
d.style.color="#00ff00";
}
function outs(){
var d=document.getElementById('count');
d.style.backgroundColor="pink";
d.style.color="black";
}
</script>
</head>
<body>
<form>
<input type="text" id="count" />
<input type="button" value="Start" onclick="startCount()" onmouseout="outs()" onmouseover="overs()"/>
<input type="button" value="Stop" onclick="stopCount()" onmouseout="outs()" onmouseover="overs()" />
</form>
</body>
</html>
