求助！！！
<!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 good =setInterval(clock,100)
function clock(){
var time = new Date();
document.getElementById("good").value=time
//此处 value代表什么意义， 我没输入"value"就不成功
}
</script>
</head>
<body>
<form>
<input type="text" id="good" size="50" />
</form>
</body>
</html>
以上代码注释行 value的含义
