Here is options (option1 and option2). If option1 is selected, the `<div id="aa">` and `<div id="bb">` should be showed and on selecting option2, `<div id="bb">` and `<div id="cc">` should be showed. how to do it using javascript? 

```
<select>
<option>option1</option>
<option>option2</option>
</select>

<div id="aa">
<table width="100%" border="0" style="text-align:center;">
<tr><td>Table 1</td></tr>
</table></div>

<div id="bb">
<table width="100%" border="0" style="text-align:center;">
<tr><td>Table 2</td></tr>
</table></div>

<div id="cc">
<table width="100%" border="0" style="text-align:center;">
<tr><td>Table 3</td></tr>
</table></div>

```