非正规写法获取不到tr,td

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
    <div id="temp">
        <tr>
            <td>dad</td>
        </tr>
        <tr>
          <td>dad</td>
        </tr>    
    </div>
        
    </body>
    <script>
        var divDom=document.getElementById("temp").innerHTML;
        console.log(divDom);
    </script>
</html>

不管怎么整都获取不到tr,td，想了半天没有想明白，最后在tr上添加table,完整了一下结果，结果出来了，说明想要获取tr,td必须在正规的写法下，例如

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>
    </head>
    <body>
    <div >
        <table id="temp">
            <tr>
                <td>dad</td>
            </tr>
            <tr>
              <td>dad</td>
            </tr>
        </table>
    </div>
        
    </body>
    <script>
        var divDom=document.getElementById("temp").innerHTML;
        console.log(divDom);
    </script>
</html>

这样就可以获取到tr,td.