JS动态添加选项案例分析

<table width="100%" class="form">
  <tr>
  <th width="100px"><label>标题1:</label></th>
  <td align="left"><input type="text" class="large" id="title" name="title" />&nbsp;<span class="error">请输入标题</span></td>
  </tr>
  <tr>
  <th width="100px"><label>选择类型:</label></th>
  <td align="left">
  <input type="radio" name="radio" />单选&nbsp;&nbsp;&nbsp;
  <input type="radio" name="boxcheck" />多选&nbsp;&nbsp;&nbsp;
  <input type="radio" name="select" />下拉&nbsp;&nbsp;&nbsp;
  </td>
  </tr>
   <tr>
  <th width="100px"><label>答案:</label></th>
    <td align="left">
       <div>
         <div style="float:left;" id="1">
           A:<input type="text" class="mimi" name="A" />
           B:<input type="text" class="mimi" name="B" />
           C:<input type="text" class="mimi" name="C" />
           D:<input type="text" class="mimi" name="D"/>
         </div>
       </div>
         <div class="more" onclick="add_ask($(this))">&nbsp;</div>
          </td>
    </tr>
</table>

function add_ask($this)
{
 var $Word ="";
  //获取前面div层数
 var $div_num = $this.prev().children().attr("id");
  //增加图层
 var $div_next_num = Number($div_num)+1;
 var $last_children_name = $this.prev().children().last().children().last().attr("name").charCodeAt();
 var $html = "<div style=\"float:left;\" id="+$div_next_num+">";
  //进行四次循环
 if($last_children_name+4 <= 90)
 {
  for(var $i=1;$i<=4;$i++)
  {
   $Word = String.fromCharCode($last_children_name + $i);
   $html += $Word+":<input type=\"text\" class=\"mimi\" name="+$Word+" />";
  }
 }else
 {
   $end = 90 - $last_children_name;
   for(var $i=1;$i<=$end;$i++)
  {
   $Word = String.fromCharCode($last_children_name + $i);
   $html += $Word+":<input type=\"text\" class=\"mimi\" name="+$Word+" />";
  }
 }
  $html += "</div>";
 $this.prev().append($html);
}