1.Html和JavaScript

<table>
    <tr>
      <th class="allCheck">
        <input type="checkbox" name="" id="checkAll"> <span class="all">全选</span>
      </th>
      <th>商品</th>
      <th>商家</th>
      <th>价格</th>
    </tr>
    <tr>
      <td>
        <input type="checkbox" name="check" class="ck">
      </td>
      <td>小米手机</td>
      <td>小米</td>
      <td>￥1999</td>
    </tr>
    <tr>
      <td>
        <input type="checkbox" name="check" class="ck">
      </td>
      <td>苹果手机</td>
      <td>苹果</td>
      <td>￥6999</td>
    </tr>
    <tr>
      <td>
        <input type="checkbox" name="check" class="ck">
      </td>
      <td>华为手机</td>
      <td>华为</td>
      <td>￥6999</td>
    </tr>
  </table>

  <script>

      //1.获取大复选框
      const checkAll = document.querySelector('#checkAll')

      //2.获取所有的小复选框
      const cks = document.querySelectorAll('.ck')

      //3.点击大复选框 注册事件
      checkAll.addEventListener('click',function(){
        // console.log(this.checkAll);

        //4.遍历所有的小复选框，让小复选框的checked = 大复选框的checked
        for(let i = 0;i < cks.length;i++){
          // cks[i].checked = checkAll.checked
          cks[i].checked = this.checked
        }

        //5.小复选框控制大复选框
        for(let i = 0; i< cks.length;i++){
          //5.1给所有的小复选框添加点击事件
          cks[i].addEventListener('click',function(){
            //判断选中的小复选框个数 是不是等于 总的小复选框个数
            //等于3就全选
            checkAll.checked = document.querySelectorAll('.ck:checked').length === cks.length
          })
        }
      })
  </script>

2.CSS样式

 <style>
    * {
      margin: 0;
      padding: 0;
    }

    table {
      border-collapse: collapse;
      border-spacing: 0;
      border: 1px solid #c0c0c0;
      width: 900px;
      margin: 100px auto;
      text-align: center;
    }

    th {
      background-color: #09c;
      font: bold 16px "微软雅黑";
      color: #fff;
      height: 24px;
    }

    td {
      border: 1px solid #d0d0d0;
      color: #404060;
      padding: 10px;
    }

    .allCheck {
      width: 80px;
    }
  </style>