当前时间实时刷新js

var t = null;
t = setTimeout(time,1000);
function time(){
    clearTimeout(t);
    dt = new Date();
    var y = dt.getFullYear();
    var mt = dt.getFullMonth();
    var day = dt.getDate();
    var h =  dt.getHours();
    var m = dt.getMinutes();
    var s = dt.getSeconds();
    document.querySelector('.showTime').innerHTML = '当前时间' +  y + '年' + mt + '月' + day + '日' + '&ensp' + h + '时' + m + '分' + s + '秒';
    t = setTimeout(time,1000);
}