function changeBorder() { document.getElementById('myTable').border="10" }
<table border="1" id="myTable"> <tbody> <tr> <td>100</td> <td>200</td> </tr> <tr> <td>300</td> <td>400</td> </tr> </tbody> </table> <br> <input type="button" onclick="changeBorder()" value="改变边框">