加减 script函数初识

 <!DOCTYPE html>

 <html lang="en">

 <head>

     <meta charset="UTF-8">

     <title>Title</title>

     <style>

         body{

             margin: 0;

         }

         .c1{

             top: 10px;

             left: 10px;

             position: relative;

             width: 150px;

             height: 22px;

             border: 1px solid black;

             padding-right: -22px;

         }

         .c2{

             position: absolute;

             width: 22px;

             height: 22px;

             line-height: 22px;

             text-align: center;

             background-color: #dce7f4;

             border-right: 1px solid black;

             cursor: pointer;

         }

         .c3{

         }

         .c3 input{

             border: 0;

             padding: 0;

             position: absolute;

             left: 23px;

             width: 104px;

             height: 22px;

             line-height: 22px;

             text-align: center;

         }

         .c4{

             right: 0;

             position: absolute;

             width: 22px;

             height: 22px;

             line-height: 22px;

             text-align: center;

             border-left: 1px solid black;

             background-color: #dce7f4;

             cursor: pointer;

         }

     </style>

 </head>

 <body>

     <div class="c1">

         <div class="c2" onclick="Minus()">-</div>

          <div class="c3">

             <input type="text" id="count" value="0" />

         </div>

         <div class="c4"  onclick="Plus()">+</div>

     </div>

     <script type="text/javascript">

         //定义函数

         function Plus() {

             var old_str = document.getElementById('count').value;

             try{

                 var old_int = parseInt(old_str);

             }catch(e){

                 var old_int = 1

             }

             var new_int = old_int + 1;

             document.getElementById('count').value = new_int;

         }

         function Minus() {

             var old_str = document.getElementById('count').value;

             try{

                 var old_int = parseInt(old_str);

             }catch(e){

                 var old_int = 1

             }

             var new_int = old_int - 1;

             document.getElementById('count').value = new_int;

         }

     </script>

 </body>

 </html>
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加减 script函数初识

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