<input type="text" value="我是输入的文字"  maxlength="10" id="detail1"/>
<p><span id="detail1_num">0</span>/<span>10</span></p>

<textarea placeholder="最多输入100字" rows="3" maxlength="100" class="editDetail" id="detail2" >呵呵</textarea>
<p><span id="detail2_num">0</span>/<span>100</span></p>

 1 $(function(){        
 2         /*input字数*/
 3         /*在页面刚载入时先显示出输入框的字数*/
 4         var text1=$("#detail1").val();
 5         var counter1=text1.length;
 6         $("#detail1_num").text(counter1);
 7         /*添加触发事件进行动态计算输入框的字数*/
 8         $("#detail1").on(‘blur keyup input‘,function(){
 9             var text=$("#detail1").val();
10             var counter=text.length;
11             $("#detail1_num").text(counter);
12         });
13        /* textarea字数*/
14         var text2=$("#detail2").val();
15         var counter2=text2.length;
16         $("#detail2_num").text(counter2);
17         $("#detail2").on(‘blur keyup input‘,function(){
18             var text=$("#detail2").val();
19             var counter=text.length;
20             $("#detail2_num").text(counter);
21         });
22 });