JS修改alert函数样式的方法

转自：http://www.rjkfw.com/s_2098.html

<script language="javascript" type="text/javascript">

    window.alert = function(txt)

    {

     var shield = document.createElement("DIV");

     shield.id = "shield";

     shield.style.position = "absolute";

     shield.style.left = "0px";

     shield.style.top = "0px";

     shield.style.width = "100%";

     shield.style.height = document.body.scrollHeight+"px";

     shield.style.background = "#333";

     shield.style.textAlign = "center";

     shield.style.zIndex = "10000";

     shield.style.filter = "alpha(opacity=0)";

     var alertFram = document.createElement("DIV");

     alertFram.id="alertFram";

     alertFram.style.position = "absolute";

     alertFram.style.left = "50%";

     alertFram.style.top = "50%";

     alertFram.style.marginLeft = "-225px";

     alertFram.style.marginTop = "-75px";

     alertFram.style.width = "450px";

     alertFram.style.height = "150px";

     alertFram.style.background = "#ccc";

     alertFram.style.textAlign = "center";

     alertFram.style.lineHeight = "150px";

     alertFram.style.zIndex = "10001";

     strHtml = "<ul style="list-style:none;margin:0px;padding:0px;width:100%"> ";

     strHtml += " <li style="background:#DD828D;text-align:left;padding-left:20px;font-size:14px;font-weight:bold;height:25px;line-height:25px;border:1px solid #F9CADE;">[系统提示]</li> ";

     strHtml += " <li style="background:#fff;text-align:center;font-size:12px;height:120px;line-height:120px;border-left:1px solid #F9CADE;border-right:1px solid #F9CADE;">"+txt+"</li> ";

     strHtml += " <li style="background:#FDEEF4;text-align:center;font-weight:bold;height:25px;line-height:25px; border:1px solid #F9CADE;"><input type="button" value="确 定" onclick="doOk()" /></li> ";

     strHtml += "</ul> ";

     alertFram.innerHTML = strHtml;

     document.body.appendChild(alertFram);

     document.body.appendChild(shield);

     var c = 0;

     this.doAlpha = function(){

         if (c++ > 20){clearInterval(ad);return 0;}

         shield.style.filter = "alpha(opacity="+c+");";

     }

     var ad = setInterval("doAlpha()",5);

     this.doOk = function(){

         alertFram.style.display = "none";

         shield.style.display = "none";

     }

     alertFram.focus();

     document.body.onselectstart = function(){return false;};

    }

</script>