var attime;
  function clock(){
    var time=new Date();         
    var hour=aa(time.getHours());
    var minute=aa(time.getMinutes());
    var second=aa(time.getSeconds());
    attime=hour+":"+minute+":"+second;
    document.getElementById("clock").value = attime;
  }
  function aa(x){
      if(x<10)
      {
          return "0"+x;
      }else{
          return x;
      }
  }
  setInterval(clock,100)；

window.onload = function(){
var HH = 0;
var mm = 0;
var ss = 0;
var str = '';
var timer = setInterval(function(){
str = "";

if(++ss==60)
{
if(++mm==60)
{
HH++;
mm=0;
}
ss=0;
}

str+=HH<10?"0"+HH:HH;
str+=":";
str+=mm<10?"0"+mm:mm;
str+=":";
str+=ss<10?"0"+ss:ss;
document.getElementById("d").innerHTML = str;
},1000);
};

   var i;

   function sj()

  {

     var js=new Date();

    document.getElementById("xs").value=js.getHours()+"时"+js.getMinutes()+"分"+js.getSeconds()+"秒";

  }setInterval("sj()",1000);

定义了一个input，id为"xs"