html頁面動態顯示時間

思路：使用setInterval一直調用獲取當前時間方法

setInterval(getCurrentTime, 1000)


getCurrentTime () {
    let now = new Date ();
    let hh = now.getHours();
    let mm = now.getMinutes() > 10 ? now.getMinutes() : '0'+now.getMinutes();
    let ss = now.getSeconds() > 10 ? now.getSeconds() : '0'+ now.getSeconds();   
    this.currentTime = hh + ':' + mm + ':' + ss       
}