setInterval(function () {
    let dt = new Date();
    var y = dt.getFullYear();
    var mt = dt.getMonth()+1;
    var day = dt.getDate();
    var h = dt.getHours();
    var m = dt.getMinutes();
    var s = dt.getSeconds();
    document.getElementById('showTime').innerHTML =y+'年'+mt+'月'+day+'日'+h+'时'+m+'分'+s+'秒';
}, 1000);