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//promptwindow.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 = "