js获取两个时间相隔天数

           var dt1 = '2013-11-11'
            var dt2 = '2013-10-12'
            dt1 = dt1.substr(0, dt1.indexOf(" ")).replace(/-/g, "/");
            dt2 = dt2.substr(0, dt2.indexOf(" ")).replace(/-/g, "/");
            var day = (new Date(dt1) - new Date(dt2)) / (1000 * 60 * 60 * 24)  //比较两个之间的相隔天数

            alert(day);