js选中下拉框项自动提交表单

<form action="/Admin/News/insert" method="POST" > 
    <table width="100%" cellspacing="0" style="font-size:12px;"> 
       <tbody> 
            <tr> 
            <td width="100" align="center">请选择模型：</td> 
            <td align="left"> 
           <select name="modelid" id="modelid" onChange="document.all.dosubmit.click()"> 
         <option value="0">模型</option>   
            <volist name="mlist" id="mo"> 
              <if condition="$modelid eq $mo['modelid']">  
               <option value="$mo['modelid']" selected>{$mo['model']} </option> 
              <else />    
                <option value="{$mo['modelid']}">{$mo['model']}</option>  
              </if> 
              
               </volist>        
                           
        </select>         
      <input  type="submit"  name='dosubmit' style="display: none;" value="提交" />   
          </td>    
        </tr> 
   </form>