javascript动态改变当前页面中元素的状态行为

function Datea() {

           var timed = document.getElementById('timed');           var t = setInterval(function TDate() {               var d1 = new Date()               var h = d1.getHours();               var m = d1.getMinutes()               var s = d1.getSeconds()               //要判断如果h,m,s小于10的情况               h1 = h < 10 ? '0' + h : h               m1 = m < 10 ? '0' + m : m               s1 = s < 10 ? '0' + s : s               var str = h1 + ':' + m1 + ':' + s1;               // console.log(str)               if (str >= '00:00:00' && str < "12:00:00") {                   timed.innerHTML = '上午好'                   return               } else if (str >= "12:00:00" && str < "18:00:00") {                   timed.innerHTML = '下午好'                   return               } else if (str >= "18:00:00" && str < "24:00:00") {                   timed.innerHTML = '晚上好'                   return               }

           }, 1000)       }       Datea();