<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <style>
      /* 填写样式 */
    </style>
  </head>

  <body>
    <div class="box"></div>
    <!-- 填写标签 -->
    <script type="text/javascript">
      function modifyText() {
        // 补全代码
        let item = document.getElementsByClassName("box")[0];
        item.innerText = "欢迎来到牛客网";
      }
    </script>
  </body>
</html>