var h = document.getElementById("h");
var m = document.getElementById("m");
var s = document.getElementById("s");

function setTime(){
var date = new Date();

//思路：設置秒針旋轉角度;60 = 360deg; 1 = 6deg;
var seceonds = date.getSeconds();//獲取當前秒數
s.style.transform=" rotate("+6*senconds+"deg)";
//(style中的樣式transform =rotate(x deg))旋轉多少度；
// 60分鐘 = 360deg 1分鐘=6deg;
var minutes = date.getMinutes();
m.style.transform = "rotate(" + 6 * minutes + "deg)";
//設置時針
//12小時 = 360deg 1小時=30deg
var hours = date.getHours();
h.style.transform = "rotate(" + 30 * hours + "deg)";
}
setTime();函數調用執行
setInterval(setTime,1000);