function openApp(){
            if(navigator.userAgent.match(/(iPhone|iPod|iPad);?/i)) {
                var loadDateTime = new Date();
                window.setTimeout(function() {
                    var timeOutDateTime = new Date();
                    if(timeOutDateTime - loadDateTime < 5000) {
                        window.location = "要跳转的下载app页面URL";
                    } else {
                        window.close();
                    }
                },25);
                window.location = " apps custom url schemes ";
            } else if(navigator.userAgent.match(/android/i)) {
                var loadDateTime = new Date();
                var state = window.open("apps custom url schemes ", ‘_blank‘);
                window.setTimeout(function() {
                    var timeOutDateTime = new Date();
                    if(timeOutDateTime - loadDateTime < 5000) {
                        window.location = "要跳转的下载app页面URL";
                    } else {
                        window.close();
                    }
                },25);
            }
        }