Js实例之简易计算器

 1 <html>
 2     <head>
 3         <title>简易计算器（二）</title>
 4         <script type="text/javascript">
 5         function doCal(){
 6         var value1 = parseInt(document.getElementById("value1").value);
 7         var value2 = parseInt(document.getElementById("value2").value);
 8         var flag = document.getElementById("flag").value;
 9         var s = 0;
10         eval("s=value1"+flag+"value2");
11         document.getElementById("span1").innerHTML ="<font color='red'>" +s+"</font>";
12         alert(s);
13         }
14         </script>
15     </head>
16     <body>
17         <input type="text" id="value1">
18         <select id="flag">
19         <option>+</option>
20         <option>-</option>
21         <option>*</option>
22         <option>/</option>
23         </select>
24         <input type="text" id="value2">
25         <input type="button" id="=" value="=" onClick="doCal()">
26         <span id="span1"></span>
27     </body>
28 </html>
收获：获取值然后要转换为int型的，eval的使用