window.alert = function(str) {
var alertBox = document.createElement("div");
alertBox.id="alertBox";
alertBox.style.position = "absolute";
alertBox.style.width = "400px";
alertBox.style.background = "#F2F2F2";
alertBox.style.border = "1px solid grey";
alertBox.style.left = "50%";
alertBox.style.top = "50%";
alertBox.style.transform = "translate(-50%, -50%)";
alertBox.style.textAlign = "center";
alertBox.style.zIndex = "100";
var strHtml = "";
strHtml += '<div id="title">提示：<div id="close" οnclick="certainFunc()"></div></div>';
strHtml += '<div id="content">'+str+'</div>';
strHtml += '<div id="certain"><input id="btn" type="button" value="确 定" οnclick="certainFunc()" onhover="hoverFunc()"/></div>';
alertBox.innerHTML = strHtml;
document.body.appendChild(alertBox);
var title = document.getElementById("title");
title.style.textAlign = "left";
title.style.marginTop = "20px";
title.style.paddingLeft = "20px";
title.style.height = "30px";
title.style.fontSize = "15px";
var close = document.getElementById("close");
close.style.width = "16px";
close.style.height = "16px";
close.style.marginRight = "20px";
close.style.background = "url('images/close.png')";
close.style.float = "right";
var content = document.getElementById("content");
content.style.margin = "20px";
content.style.fontSize = "12px";
var certain = document.getElementById("certain");
certain.style.position = "relative";
certain.style.height = "50px";
certainFunc = function() {
alertBox.parentNode.removeChild(alertBox);
};
var btn = document.getElementById("btn");
btn.style.width = "60px";
btn.style.height = "30px";
btn.style.background = "#cccccc";
btn.style.border = "1px solid grey";
btn.style.position = "absolute";
btn.style.borderRadius = "5px";
btn.style.right = "20px";
btn.style.bottom = "20px";
btn.style.marginTop = "10px";
btn.style.cursor = "pointer";
btn.style.color = "#333";
hoverFunc = function() {
btn.style.border = "1px blue solid";
};
}