js引出函数概念的案例

 1 <!DOCTYPE html> 2 <html> 3   <head> 4     <meta charset="utf-8"> 5     <title></title> 6     <script> 7       /*输入两个数，再输入一个运算符，得到结果*/ 8       var num1 = window.prompt("请输入第一个数"); 9       num1=parseFloat(num1);10       var num2 = window.prompt("请输入第二个数");11       num2=parseFloat(num2);12       var oper = window.prompt("请输入运算符");13       var res = 0;14       switch(oper)15       {16         case "+":17           res = num1 + num2;18           document.write(num1+oper+num2+"="+res);19           break;20         case "-":21           res = num1 - num2;22           document.write(num1+oper+num2+"="+res);23           break;24         case "*":25           res = num1 * num2;26           document.write(num1+oper+num2+"="+res);27           break;28         case "/":29           res = num1 / num2;30           document.write(num1+oper+num2+"="+res);31           break;32         defult:document.write("输入错误");33       }34     </script>35   </head>36   <body>37   </body>38 </html>

 1 //jisuan.js 2 function p(){ 3   /*输入两个数，再输入一个运算符，得到结果*/ 4   var num1 = window.prompt("请输入第一个数"); 5   num1=parseFloat(num1); 6   var num2 = window.prompt("请输入第二个数"); 7   num2=parseFloat(num2); 8   var oper = window.prompt("请输入运算符"); 9   var res = 0;10   switch(oper)11   {12     case "+":13       res = num1 + num2;14       document.write(num1+oper+num2+"="+res);15       break;16     case "-":17       res = num1 - num2;18       document.write(num1+oper+num2+"="+res);19       break;20     case "*":21       res = num1 * num2;22       document.write(num1+oper+num2+"="+res);23       break;24     case "/":25       res = num1 / num2;26       document.write(num1+oper+num2+"="+res);27       break;28     defult:document.write("输入错误");29   }30   31 32 }

 1 <!--putong.html--> 2  3 <!DOCTYPE html> 4 <html> 5   <head> 6     <meta charset="utf-8"> 7     <title>调用函数实现计算功能</title> 8     <script src='/images/loading.gif' data-original="jisuan.js" type="text/javascript"></script> 9   </head>10   <body>11     <input type="button" value="点我开始计算" onclick="p()">12   </body>13 </html>

运行效果如下图所示：