JavaScript 获取系统当前时间并动态显示的实现方法

<!DOCTYPE html>
<html>
<head>
  <title>获取时间</title>
  <script type="text/javascript">
  window.onload = function(){
    showTime();
  }

  function showTime(){
    var myDate = new Date();
    var year = myDate.getFullYear();
    var month = myDate.getMonth() + 1;
    var date = myDate.getDate();
    var dateArr = ["日","一",'二','三','四','五','六'];
    var day = myDate.getDay();
    var hours = myDate.getHours();
    var minutes = formatTime(myDate.getMinutes());
    var seconds = formatTime(myDate.getSeconds());

    var systemTime = document.getElementById("time");
    systemTime.innerHTML = " " + year + "年" + month +"月" + date + "日" + " 星期" + dateArr[day] + " " + hours + ":" + minutes + ":" + seconds;
    setTimeout("showTime()",500);
  }

  //格式化时间：分秒。
  function formatTime (i){
    if(i < 10){
      i = "0" + i;
    }
    return i;
  }

  </script>
</head>
<body>
  <div id ='time'></div>
</body>
</html>