jq 监听返回事件

    <script>

 $(document).ready(function(e) {
            var counter = 0;
            if (window.history && window.history.pushState) {
                             $(window).on('popstate', function () {
                                            window.history.pushState('forward', null, '#');
                                            window.history.forward(1);
                                          alert("不可回退");
                                          //window.location="./c.html";
                                });
              }

              window.history.pushState('forward', null, '#'); //在IE中必须得有这两行
              window.history.forward(1);
});
    </script>