哪位大哥帮帮忙，解决下这个小问题，妹纸我是菜鸟一只，在此先谢谢了
我想选择键盘上的数字或字母，让它显示在上面那个textbox里，js代码怎么写


<div class="note" align="center">
      <p>Please key in or scan your NRIC or T-pass:</p> 
      <form  action="ssk_2.html" >
     <input class="textbox" type="text"   id="textfile" size="60"   /><br />
     <input class="submit" type="submit" value="Submit">
      </form>
   </div> 
   <div class="keyboarddiv">
     <table class="keyboardtable" cellspacing="5px" cellpadding="0" width="761px">
   <tr>
   <td>

   <button id="1" class="keyboardbutton" value="1" onclick="SetValue(this)">
1
</button>
   </td>
    
   <td>
<button  id="2"class="keyboardbutton">
2
</button>
   </td>
 <td>
   <button class="keyboardbutton">
3
   </button>
   </td>
 <td>
   <button class="keyboardbutton">
4
   </button>
   </td>
   <td>
   <button class="keyboardbutton">
5
   </button>
   </td>
<td>
   <button class="keyboardbutton">
6
   </button>
   </td>
   <td>
   <button class="keyboardbutton">
7
   </button>
   </td>
 <td>
   <button class="keyboardbutton">
8
   </button>
   </td>
 <td>
   <button class="keyboardbutton">
9
   </button>
   </td>
<td>
   <button class="keyboardbutton">
0
   </button>
   </td>
   </tr>
   <tr>
<td>
   <button class="keyboardbutton">
Q
   </button>
   </td>
   <td>
   <button class="keyboardbutton">
W
   </button>
   </td>
 <td>
   <button class="keyboardbutton">
E
   </button>
   </td>
 <td>
   <button class="keyboardbutton">
R
   </button>
   </td>
   <td>
   <button class="keyboardbutton">
T
   </button>
   </td