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 <script type="text/javascript">
    //获取客户端实例
        var pa = Sys.WebForms.PageRequestManager.getInstance();
        function CanceAsynPostBack() {
        //判断客户端生命周期是否处理异步回发状态
            if (pa.get_isInAsyncPostBack()) {
            //中断回发
                pa.abortPostBack();
             }
         }
    </script>