在网页中居中显示今天是星期几在网页中居中显示今天是星期几，document.getElementByld("day")的


<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <title>switch语句实例</title>
  </head>
  <style></style>
  <body>
    <h1 align="center">今天是<span id="day"></span></h1>
    <script>
      var d = new Date(); 
      var week = d.getDay(); 
      var day = document.getElementById("day");
      switch (week) {
        case 0:
          day.innerHTML = "星期日";
          break;
        case 1:
          day.innerHTML = "星期一";
          break;
        case 2:
          day.innerHTML= "星期二";
          break;
        case 3:
          day.innerHTML = "星期三";
          break;
        case 4:
          day.innerHTML = "星期四";
          break;
        case 5:
          day.innerHTML = "星期五";
          break;
        case 6:
          day.innerHTML = "星期六";
          break;
        default:
      }
    </script>
  </body>
</html>

其中，document.getElementByld("day")的作用是获取页面中id=day的元素，day.innerHTML的作用是对页面中相应的元素进行插入内容。