SOURCE

   function getD1(){  
        var date=new Date();  
        var date1=date.toLocaleString();  
        var div1=document.getElementById("divid");  
        div1.innerHTML=date1;  
  }  
    setInterval("getD1();",1000); 
(()=>{
   var myDate = new Date(); 
myDate.getYear(); //获取当前年份(2位) 
myDate.getFullYear(); //获取完整的年份(4位,1970-????) 
myDate.getMonth(); //获取当前月份(0-11,0代表1月) 
myDate.getDate(); //获取当前日(1-31) 
myDate.getDay(); //获取当前星期X(0-6,0代表星期天) 
myDate.getTime(); //获取当前时间(从1970.1.1开始的毫秒数) 
myDate.getHours(); //获取当前小时数(0-23) 
myDate.getMinutes(); //获取当前分钟数(0-59) 
myDate.getSeconds(); //获取当前秒数(0-59) 
myDate.getMilliseconds(); //获取当前毫秒数(0-999) 
myDate.toLocaleDateString(); //获取当前日期 
var mytime=myDate.toLocaleTimeString(); //获取当前时间 
myDate.toLocaleString(); //获取日期与时间 
function ShowTime() { 
var time = new Date(); 
var temp = time.toLocaleString(); 
document.getElementById("spanTime").innerHTML = temp; 
setTimeout(ShowTime, 1000); 
} 
window.onload = ShowTime(); 
})

<div id='yh'></div>
	<div id="divid">  
  
	  </div> 

 #yh{
            width: 0;
            height:0;
            border-left:50px solid transparent;
            border-right: 50px solid transparent;
            border-bottom: 100px solid red;
        }