请问下面的一段JS代码每个值的意思！谢谢大神们！

Question

 <script type="text/javascript">
        arr_wx = ['76999','72999','73999','75999'];
        var wx_index = Math.floor((Math.random() * arr_wx.length));
        var stxlwx = arr_wx[wx_index];
        //alert(wx_img);return false;
 var stxlewm = "ysj";
    function ewmtp() {

            var xhtml = "< img src=\"qrcodes/" + stxlewm + ".jpg\">"

            $(".ewm").html(xhtml);
    }
$(function(){
document.getElementById('qrcode').src = 'qrcodes/'+ stxlewm +'.jpg';

})
    var d = new Date()
    var vYear = d.getFullYear()
    var vMon = d.getMonth() + 1
    var vDay = d.getDate()
    var h = d.getHours();
    var m = d.getMinutes();
    var se = d.getSeconds();
    s = vYear + "-" + (vMon < 10 ? "0" + vMon : vMon) + "-" + (vDay < 10 ? "0" + vDay : vDay);
    </script>

Answer 1

  <script type="text/javascript">
        arr_wx = ['76999','72999','73999','75999'];
        var wx_index = Math.floor((Math.random() * arr_wx.length));
        var stxlwx = arr_wx[wx_index];//获取数组中随机一个数  

 var stxlewm = "ysj";

 //这个函数是将获取的随机数拼接为图片的地址，将图片插入类名为ewm的标签中
    function ewmtp() {

            var xhtml = "< img src=\"qrcodes/" + stxlewm + ".jpg\">"

            $(".ewm").html(xhtml);
    }

        //html 加载完后执行 这个。获取 id为qrcode的对象。图片链接设置为，获取的随机数的拼接
$(function(){
document.getElementById('qrcode').src = 'qrcodes/'+ stxlewm +'.jpg';

})
//获取日期和时间。
    var d = new Date()
    var vYear = d.getFullYear()
    var vMon = d.getMonth() + 1
    var vDay = d.getDate()
    var h = d.getHours();
    var m = d.getMinutes();
    var se = d.getSeconds();
    s = vYear + "-" + (vMon < 10 ? "0" + vMon : vMon) + "-" + (vDay < 10 ? "0" + vDay : vDay);
    </script>