怎样实现输入文本框和列表实现联动?
<form name="form" method="post" action="">
输入:<input name="textsize" type="text" size="20" maxlength="20">
型号:
<select name="size" size="4">
<option value="1210-1">1210-1</option>
<option value="1210-2" selected>1210-2</option>
<option value="1210-3">1210-3</option>
<option value="1220-1">1220-1</option>
<option value="1220-2">1220-2</option>
<option value="1220-3">1220-3</option>
<option value="2100-1">2100-1</option>
<option value="2100-2">2100-2</option>
<option value="2100-3">2100-3</option>
<option value="2100-4">2100-4</option>
<option value="2120-1">2120-1</option>
<option value="2120-2">2120-2</option>
<option value="2120-3">2120-3</option>
<option value="3110-1">3110-1</option>
<option value="3110-2">3110-2</option>
<option value="3220-1">3220-1</option>
<option value="3220-2">3220-2</option>
<option value="7110-1">7110-1</option>
<option value="7110-2">7110-2</option>
<option value="7110-3">7110-3</option>
<option value="7210-1">7210-1</option>
<option value="7210-2">7210-2</option>
<option value="8550-1">8550-1</option>
<option value="8551-2">8551-2</option>
</select>
</form>
要求在文本框中输入型号的前1-4位,后面的列表框选择就移动到相应的位置,例如输入"7110"则列表框选择就移动到"7110-1"的位置?谢谢!!!