<html>
<head>
<title>在指定的时间调用一次函数</title>
<script language="javascript">
<!--
function showtxt(){
a = txt.value;
txt.value = a + "*";
}
setTimeout("showtxt()",2000);
//-->
</script>
</head>
<body>
<input type="text" id="txt">
</body>
</html>