先看图：
具体代码：
window.alert = function (txt, time) {if (document.getElementById("alertFram")) {return;}var alertDiv = document.createElement("DIV");alertDiv.id = "alertFram";alertDiv.style.position = "absolute";alertDiv.style.left = "50%";alertDiv.style.top = "40%";alertDiv.style.marginLeft = "-225px";alertDiv.style.marginTop = "-75px";alertDiv.style.width = "450px";alertDiv.style.height = "340px";alertDiv.style.background = "#ccc";alertDiv.style.textAlign = "center";alertDiv.style.zIndex = "10000";alertDiv.innerHTML = '<div style="width: 100%;height: 100%;background: #fff;border: 1px solid #f1f1f1;overflow: hidden;"><div style="font-size: 16px;text-align: center;line-height: 42px;color: #111;background: #fff;position: absolute;left: 0;top: 0;z-index: 999;width: 100%;text-align: center;border-bottom:1px solid #F0F0F0">详情</div><div style="text-align: left;margin-top: 42px;font-size: 14px;padding: 10px;color: #555;height: 82%;overflow: auto;word-wrap: break-word;">'+ txt +'</div><div style="position: absolute;right: 10px;top: 3px;font-size: 24px;cursor: pointer;z-index: 1000;" onclick="doOk()">×</div></div>';document.body.appendChild(alertDiv);var c = 0;this.timer = function () {if (c++ >= time) {clearInterval(ad);document.body.removeChild(alertDiv);}}var ad = setInterval("timer()", 1000);this.doOk = function () {document.body.removeChild(alertDiv);}alertDiv.focus();document.body.onselectstart = function () {return false;};}
