jQuery动态添加input，name值自增

    function addLi(){
        var listNum=$(".divList").length;
        var num= listNum == 0 ? 1: listNum+1 ;
        console.log(num);
        var divObj = '<div class="divList"><input class="small_input" placeholder="起始年份" name="start_year'+num +'" /><input class="small_input" placeholder="结束年份" name="end_year'+num +'" /><input class="small_input" placeholder="国家" name="country'+num +'" /><input class="small_input" placeholder="项目金额" name="item_amount'+num +'"  /><input class="small_input" placeholder="项目名称" name="item_name'+num +'" /></div>'
        $('.main_business').append(divObj);
        var input_sum_val=$(".input_sum").val()
      $(".input_sum").val(++input_sum_val);
    }

       <dd style="height: auto;">
            <label>主营业务</label>
            <input class="input_sum" type="hidden" name="max" value="1" />
            <div class="main_business">
                <input class="small_input" placeholder="起始年份"><input class="small_input" placeholder="结束年份">
                <input class="small_input" placeholder="国家"><input class="small_input" placeholder="项目金额"><input class="small_input" placeholder="项目名称">
            </div>
           <button onclick="addLi()">add</button>
        </dd>