初级的计时器

<div>
    <p id="p"></p>
    <p id="w"></p>
</div>

=====================CSS=========================

#p {
padding-top:30px;
padding-left:30px;
color:white;
}
div {
width:250px;
height:300px;
background-color:blue;
margin:10px auto;
}
#w {
width:120px;
height:120px;
background-color:green;
display:inline-block;
margin:60px;
text-align:center;
line-height:120px;
color:pink;
font-size:50px;
}

==========================JS================================

setInterval(function() {
    var date = new Date;
    var p = document.getElementById("p");
    var arr = ["星期天", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"]
    var a = date.getFullYear() + '年' + (date.getMonth() + 1) + '月' + date.getDate() + '日' + arr[date.getDay()] + date.getHours() + '小时' + date.getMinutes() + '分钟' + date.getSeconds() + '秒' + date.getMilliseconds() + '毫秒';
    p.innerHTML = a;
    var w = document.getElementById("w");
    var e = date.getDate();
    w.innerHTML = e;
}, 1000)