2중 셀렉트 질문드립니다. 채택완료

</p><p>select name="product" id="product" class="cis"></p><p><option value="">선택하세요</option></p><p><option value="0001">가</option></p><p><option value="0002">나</option></p><p><option value="0003">다</option></p><p></select> </p><p><select name="model" id="model" class="cis"></p><p><option value="">선택하세요</option></p><p></select></p><p><script type="text/javascript" language="javascript"></p><p>var model_value=new Array();</p><p>model_value[가]='a,b,c';</p><p>model_value[나]='e,f,g';</p><p>$(function() {</p><p style="margin-left: 40px;">$("#product").bind("change", function() {</p><p style="margin-left: 80px;">var model=$(this).val();</p><p style="margin-left: 80px;">chang_model(model);</p><p style="margin-left: 40px;">});​</p><p>});</p><p>function chang_model(model)</p><p>{</p><p style="margin-left: 40px;">var model_id=document.getElementById("model");</p><p style="margin-left: 40px;">model_id.options.length = 1;
model_id.options[0].selected = true;
model_id.options[0].text  = "선택하세요";
model_id.options[0].selected = true;​</p><p style="margin-left: 40px;">num=model_value[model].split(",");</p><p style="margin-left: 40px;">num_l=num.length;</p><p style="margin-left: 40px;">model_id.option.length=num_l+1;</p><p style="margin-left: 40px;">for(i=0;i<num_l;i++)</p><p style="margin-left: 40px;">{</p><p style="margin-left: 80px;">model_id.option[i+1].value=num[i];</p><p style="margin-left: 80px;">model_id.option[i+1].text=num[i];</p><p style="margin-left: 40px;">}</p><p>}</p><p></script></p><p>