js点击列表中的2跟3互换位置

现在数据渲染了12345678然后举例1身上有一左一右按钮点击向右的时候1和2互换位置，不发请求，就js操作。


<!--
 * @Author: your name
 * @Date: 2021-12-30 16:59:23
 * @LastEditTime: 2022-03-08 20:47:57
 * @LastEditors: Please set LastEditors
 * @Description: 打开koroFileHeader查看配置 进行设置: https://github.com/OBKoro1/koro1FileHeader/wiki/%E9%85%8D%E7%BD%AE
 * @FilePath: /未命名文件夹/123.html
-->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <div class="box"></div>
    <button class="left">left</button>
    <button class="right">right</button>
    <script>
      window.onload = function () {
        var num = 0;
        var a = "123456789";
        document.querySelector(".box").innerHTML = a;
        function change(arr, k, j) {
          var c = arr[k];
          arr[k] = arr[j];
          arr[j] = c;
          a = arr.join("");
          document.querySelector(".box").innerHTML = arr.join("");
        }
        document.querySelector(".left").onclick = function () {
          if (num == 0) return;
          change(a.split(""), num, num - 1);

          num--;
        };
        document.querySelector(".right").onclick = function () {
          if (num == 8) return;
          change(a.split(""), num, num + 1);
          num++;
        };
      };
    </script>
  </body>
</html>

变量试试