浏览器关闭 弹出提示

浏览器关闭 弹出提示

<script type="text/javascript">    window.a = 0;    var rv = "确定要关闭吗？";    window.onbeforeunload = function () {        var isIE = document.all ? true : false;        if (isIE) {            var n = window.event.screenX - window.screenLeft;            var b = n > document.documentElement.scrollWidth - 20;            if (b && window.event.clientY < 0 || window.event.altKey) {                //是关闭而非刷新                window.event.returnValue = rv;            }        } else {            if (document.documentElement.scrollWidth != 0) {                if (window.a != 1) {                    window.a = 0;                    return rv;                } else {                    window.a = 0;                }            }            else {                window.a = 0;                return rv;            }        }    }</script>