js重写alert事件，避免alert弹框标题出现网址

js代码：window.alert = function(msg, callback) { var div = document.createElement("div"); div.innerHTML = "<style type=\"text/css\">" + ".nbaMask { position: fixed; z-index: 1000; top: 0; right: 0; left: 0; bottom: 0; background: rgba(0, 0, 0, 0.5