js中三种弹窗
1）alert 弹出警告 无返回值－－－－－－－－－alert('第一行\n第二行');
2）confirm()选择确定或取消，返回t或f－－－－var result = confirm('是否删除！');
3）prompt()弹出输入框，返回输入内容－－－－var value = prompt('输入你的名字：', '请在这里输入名字');
当然也可以自定义好看的样式。下面代码有问题明天再改。
<script>
//window.confirm
//prompt
window.alert = function(title,str)
{
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";
//弹出对话框时的背景颜色
shield.style.background = "#fff";
shield.style.textalign = "center";
shield.style.zindex = "25";
//背景透明 ie有效
//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 = "#ff0000";
alertfram.style.textalign = "center";
alertfram.style.lineheight = "150px";
alertfram.style.zindex = "300";
strhtml = "<ul style=\"list-style:none;margin:0px;padding:0px;width:100%\">\n";
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;\">" + title + "</li>\n";
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;\">" + str + "</li>\n";
strhtml += " <li style=\"background:#fdeef4;text-align:center;font-weight:bold;height:25px;line-height:25px; border:1px solid #e85727;\"><input type=\"button\" value=\"确 定\" onclick=\"dook()\" /></li>\n";
strhtml += "</ul>\n";
alertfram.innerhtml = strhtml;
document.body.appendchild(alertfram);
document.body.appendchild(shield);
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>